Many people lack the cold-bloodedness necessary to be that mercenary. Especially game devs, who are almost always in it for the love of the product, not for a paycheck. Corporate may not be their friend, but the product they're creating is their creation. Every person working on it knows a hundred things they could do to make it better, and they want to do all of them. They just need a bit more time.

Unions are about protecting everyone from predatory employers like most game publishers. You go in and negotiate? You're fired; there are 100 more people out there with a compulsion to create and share with the world.

So yeah, unions. They address the issue of the party with money exploiting the non-monetary incentives. That's strictly better than assuming the problem is that people have non-monetary incentives.