But yes your point is right on in that the unions are useless. In large part because they are a corrupt themselves and their grift is taking a vig on employment.
If something is weak (like the unions), will it ever be useful?
"Unions of type T are weak, therefore all Unions are without purpose" is not logical.
A poor implementation of a system is not a case against the system, particularly when other countries have proper implementations of the system.
(BTW I'm discussing things with the opinions given by others. I certainly don't think unions, even in the US, are particularly weak or useless. The president had to take action to prevent a particularly useful and impactful railworkers' strike last year. Teachers in Virginia got good pay raises after a strike several years ago. Writers and actors are fighting for their long-term survival against large studios.)