I think you fundamentally misunderstand unions and the worker-corporation relationship. Historically, and through to today, corporations have most/all of the power. Which is why things like child labor, 16 hour work days, etc. were very common, until workers unionized, effectively pooling their power in order to negotiate with corporations. If you didn't have to work as a child, or don't have to work longer than 8 hours, thank a union.
Not unless there is slavery. People are not forced to work for any corporation and they are free to go work for another or start their own.
>child labor
Good for children who want extra money to spend or families who don't make enough. Childhood is when most people learn the most and there are certain things that can only be learned while on the job.
>16 hour work days
Good for people who want to make more money at the same job.
>If you didn't have to work as a child, or don't have to work longer than 8 hours, thank a union.
I did work as a child and did work 16 hour days and I don't regret doing so as the money I made doing so significantly improved the trajectory of my life.