Somehow, the large investors still make lots of money. The primary effect of unions in this space seems to be that they put an actual dollar cost on poor management. When you hear about boondoggles like Heaven's Gate or Waterworld, what you hear isn't that unions screwed it up; you hear about the prima donna director who couldn't get it all "just so" with a couple hundred million to work with.
My employer, a digital services agency, pays hourly overtime of 1.5x. Then the professional PMs we have work very hard to accurately forecast and estimate. I've had crunch periods in which I've been paid overtime, but they're rare because the business has incentived itself to execute on-time and on-budget, mostly by not promising what we can't deliver and expecting the workers to pick up the slack.
Now I work for IBM, and I am expected to work late as much as it takes to ship on time. "On time" is of course completely arbitrary and determined by people who have no understanding of the technical tasks required to ship the project (and most pertinent, don't listen to me when I provide my expert opinion that the timeline is not viable). And they expect to not have to pay me for that overtime.
Not being able to exploit your workers encourages realistic deadlines.
This is such a weird logic. Since when should the company financial incentives have higher priority over the employees well-being? Arguably, if the existence of the company is threatened by a few delays and that the only solution is to exploit people, it should instead close shop and let people get other jobs that will make them happier.
So no, a union would probably not help the game be shipped in time, and if it did, it would be the shittiest union. And if enforcing humane working conditions against the profits of the employer makes the business unsustainable, this means the business should not exist in the first place.
Quite likely yes, though not directly. Foreclosing avenues that management tends to fall into which are both empirically not particularly effective and also miserable working conditions, like more than brief crunch time, probably does improve delivery, though that's not the main goal.