We go to the seaport and spend a thousand gold hiring a small force of laborers and mercenaries to excavate the ruined temple while guarding our work site from the tribal lizard-men who surround the site. Make sure to find a good captain to commend the men and an experienced crew boss to manage the workers. Oh, and we will need boats too to haul everything out - let's plan on a large haul.You spend money to get money. You spend a thousand gold because you know there are tens of thousands of coins down there in that ancient temple to haul out with pack animals (you had to buy) down narrow mountain tracks while protecting your haul from the lizard-men who see that temple as a shrine to their ancient lizard god and will do everything to keep your almost-colonial ambitions for loot and wealth in check with a poisoned spear and ritualistic shaman magic.
The hirelings? In it for the money too - probably more than they will ever see in their lifetime, so they accept the risk of being eaten by a basilisk in exchange for making what would take years with sustenance agriculture, taxes, levies, droughts, family costs, and unplanned economies that eats a hole in the bottom of the money pouch for the average peasant.
People forget medieval economics these days.
The AD&D EraBy AD&D we started to see the shift towards the more traditional "adventuring party" style of adventure, and don't worry, enough bags of holding will keep your labor costs down to a minimum. You could teleport in and out with a small team and clean out almost any location with just five people.
There were some notable mentions of large groups of hirelings being needed for adventures such as The Tomb of Horrors and others, but I don't really remember any module requiring you to manage a large group of hirelings during the time we played AD&D.
To be fair, the rules for all types of hirelings are here, but the ramp up in character and magic item power moved our games from more of an expedition-based adventure model into a super-heroic one where a small party of adventurers could do anything. Given enough gates, teleports, bags of holding, floating discs, and other cash-hauling magics there was this work multiplier with convenience magic that allowed a small group of mid-to-high level adventurers to haul huge loads. This was one of those forms of power creep that entered the game at this time, "Here's a common problem, let's solve it with magic!"
You get these types of popular wishes of players and the magic naturally rushes in to fill the void, and I wonder at times if some decisions are better left as they are, and some core concepts left alone.
AD&D 2nd Edition I felt moved farther along the "party of heroes" model and retainers moved to the back in importance. Your characters adventured alongside the heroes from the Forgotten Realms and Dragonlance - just like those characters - and who needs an army of unskilled labor weighing them down when adventure awaits! We kept the super-hero model of the iconic D&D party, based our adventures off the Tolkien-like book heroics, and never really fussed with hirelings in most cases.
D&D 3.x and PathfinderThe concept of "character build as deck build" came into play with the 3rd edition of the rules and all of its subsequent variants, and I feel retainers and hirelings moved farther back in the entire scheme of things. This is my character build, and it can take on all comers! Who needs hirelings when my character sheet is the length of a moderately complicated tax form and I am ready for any special case rule thrown my way?
Pathfinder's adventure paths are also a great example of adventures built for characters of this generation of the rules, typically focused on the party of four or five heroes and built around a mathematical challenge rating system that ensures a slow-but-steady drip-drip of resources that will be used every encounter.
And the 15-minute adventure day was born because players tended to alpha-attack the first encounter with everything they had and then headed back to the inn to rest a day before they tackled the next challenge. This was also a way to mitigate resource management and bad luck, as a bad encounter ensured you needed to bug out and rest to recover your bad situation.
But retainers and hirelings? Really pushed to the back further I feel, and the concept of putting together an expedition of NPCs and random swords for hire seemed as alien to this generation of gaming.
World of D&D 4-CraftBy D&D 4 a character was essentially an MMO character, and I don't even remember hirelings being mentioned all that much in any D&D 4 book. I am pretty sure they were mentioned somewhere but we never used them in our "battle chess" type games of tight hallways and chambers, grid based movement, and some really fun encounters during the early days of the game that we enjoyed. We never had room for hirelings on the game board since all our play were those tight, one map, small corridor and room fights the game did so well before the books piled on and the game collapsed under its own weight of revisions and expansions.
We had fun with the game, but we felt hirelings were so far removed from the game - and characters were so powerful and cool - that we never bothered with them. It felt like a cool video-game on the tabletop and that is how we played it.
Hireling NPCs rarely become important during an adventure...That quote is on page 94 of the 5e DMG, and a 2 gp a day cost for any type of skilled hireling in the PHB and that is mostly all I can find on the subject. Also, D&D 5 does not scale that well (from what I hear) with large numbers of low-level characters assisting in a battle due to the flatter dicing mechanics, so I can understand why you shouldn't really cheese your way through every fight with Robin Hood and his 20-man sheaf of merry archers in formation behind you vaporizing any enemy in the Monster Manual with vollies of longbow fire. We are still in the "party as the base heroic unit" model of adventure and game balance.
B/X Style PlayI like the focus on putting together a Tarzan-like expedition of no-name hirelings and specialists for an adventure. I like having to hire mercenaries to protect our camp and supplies, and buy (or pay) ships and crews to haul back the loot to civilization. I like worrying about our supply of pack animals and food, where we get water from, and being called away from the temple we are exploring to deal with an attack or threat to on the group we hired.
That is cool, literary stuff for me, and it feels good. I like developing interesting NPCs for these groups, mostly no-names but there may be an interesting few people in the mix to interact with and add flavor to the game. Plus this matches some of the old-time movies that I love where a brave expedition heads down to a lost jungle or Antarctica and braves all sorts of hardships and dangers while seeking the lost treasures of the ancients.
And in B/X games those extra tag-alongs are typically weak, unless they are expensive and skilled hirelings (which you can have a limited amount of). The rules are also simple enough where you could battle out most any action scene with hirelings and mercenaries thrown into the mix without spending hours running the combat.
I don't like the "magic-superhero" style of play where we loot a dungeon by opening up a gate between point A and B and shove the piles of gold through the magic portal with farm tractors. I don't like magic replacing the need for hauling tons of loot, like owning twenty bags of holding and shoving everything in them for a quick teleport home. I like difficult and limited magic in these situations, and limiting the number of "ease of use" magic items so large expeditions are still needed and the way to do things.
The heroes can still be heroes, and it does not change the cool story moments where a classic skilled five-person party is needed to get things done.
This is all interesting how things changed over the years towards more 'cinematic' and party-based play and away from the classic 'expedition to nowhere' novel-style party-plus-hirelings model of play. Tastes and styles of play change, but I find it interesting (and informative in choosing a game) to reflect back on the history of hirelings and expeditions in gaming and how everything changed over the years. It is also interesting that many B/X games faithfully keep the hireling, ship, specialist, and mercenary rules around so this era of play can survive.