The game store doesn't need a lot of employees. A few years ago it was reported that Valve only needed about 70 employees to run Steam while it generated billions of dollars in Steam fees (30% per game). It's basically free money for Valve. I bet the situation is similar for the AppStore and Google Play.

Though Unreal Engine does indeed need quite a few developers. Additionally, using UE is much cheaper (5% on games exceeding 1 milion USD gross revenue) than using Steam (30% on every game). So they not only need more developers than Valve, they also earn less money.

Steam doesn’t really attempt to gatekeep submitted content the same way that Apple or Google do so I would expect those companies to have much larger teams supporting, in mostly non-development roles. Steam support has also historically been kind of a joke (not sure if it’s improved in the last 5 years) though I don’t know if Google/Apple provide a better experience

You know what contractors are?!