I think you mis-understand that unions and coops are about employees having a say. If the employees want to work more for less in exchange for equity they can. All unions are not the same, because the union is the workers.

You say working at a startup should be worse, but really it’s trading things. You get to learn and experience more. More equity instead of higher wages, and greater access to leadership. I work at one right now, I get it. I think this is what your saying, and workers know this. A union does not preclude this arrangement. Also the people that are willing to work at a startup tend to be more invested and want more of a say in the company. If the company succeeds I argue they deserve a seat at the table as they built it along with the founders more than any investor.

So many comments in this post setup imaginary straw men for what a union would do, then argue against that. The union is the employees, and employees at startups are not trying to kill a company and gate keep jobs.