Labor Unionism, anyone up to debate?

If unions benefitted their members above what they cost, there would not need to be any laws or regulations forcing membership or payment of dues. If unions benefitted employers more than they cost them, there would not need to be any laws forcing the acceptance of them. In both cases, membership and cooperation, force would not be necessary if mutual benefit under free exchange existed.
If a worker is free to quit a job, an employer if free to fire. Workers are not slaves, and neither are those who own a business. In fact, often they switch roles, with today’s worker opening his own shop tomorrow, or today’s business owner closing his doors and taking wage or salary work instead.
To the extent that union workers in today’s regime of laws and regulations earns more then his fellow it is with wages stolen from the less skilled kept out of the market by rules created by politicians bought and paid for by unions. No one in a union makes the minimum wage, yet unions are the biggest lobbyists for these laws. Why? Because they eliminate competition for union workers. Pay for union workers goes up, and the poorest and least skilled cannot find any job at all. Their ability to develop skills is destroyed. The young and minorities are disproportionately hurt.
Unions are cartels like any other. They seek to increase their profits at the expense of others. Unions could survive and help their members by providing training, job placement, vetted workers, group insurance pools, etc. Instead they concentrate on legally excluding competition and extorting those who create jobs by risking their own money to produce goods for society.
Unions, if they can flourish without coercion and violence, are a good thing. If they cannot, it is only because they are not a net benefit to the members and the places the members desire to work.