I think the big difference between the movie industry and the games industry isn't something as simplistic as 'get unions' - its the way that the studio system works means pretty much everyone involved at a technical level works as a contractor, so there isn't that "you better crunch like shit, because your studio might close if you don't" incentive.
You get hired to do a project, you do that project, then its on to the next one.
ILM might be owned wholesale by Disney as part of their Lucasarts acquisition, but they're still a gun for hire; they'll do work for Disney, WB, Paramount, and Universal on a project by project basis. The clsoest analogue to that in videogames are middleware suppliers, and while they might be bribed / coerced into doing some crunch on an infrequent basis, ultimately they can say "nah, fuck that" to anybody too demanding and still get work and still stay in business working for the direct competitors of anyone who tries to extort work out of them.
If you're a VFX guy working at a games studio and you're pushing back on unpaid overtime or stupid amounts of crunch, you're either getting fucked in your next pay review, or looking for a completely new studio and hoping they don't do the same thing.
