If you want to see how a professional guild works as a union, see The Animation Guild.[1] TAG represents the animators at several major studios - Warner, Disney, Sony, Pixar, etc. Their contracts set minimum wages, but not maximums. Most importantly, they have serious overtime provisions - 1.5x after 8 hours a day or 40 hours in a week, 2x after 6 consecutive days of work or 14 hours in 1 day. Hollywood has "crunches", but they're rare, because of that. (This is also why film scheduling is a serious discipline while game production scheduling is not.)

[1] https://animationguild.org/ [2] https://animationguild.org/about-the-guild/organizing/