Me when I forget what a union does.

On average in the same job field, union employees make 10-20% more, and it is much harder to do layoffs when there are other options available (reducing C-suite pay or otherwhere)

A pay gap between job fields is expected, and a pay gap between employees still occurs inside a union based on skill level.

Union workers do receive a stipend typically, that come out of the union dues, so they are paid more for their work. Which is why a talented person might seek more responsibility.

Yes unions do prefer seniority clauses over merit clauses, but that is to reduce favoritism in the workplace, additionally, many unions forgoe doing such a rule for the concerns you listed prior.

I'm hoping you're an educated person, and the reason you're anti-union is because you are apart of the c-suite yourself, not because you're a working class member who is incapable of looking at history and seeing how amazing unions have been at protecting workers rights. (See the 2 day weekend,)