In what way do you believe unions are useless and bad? That's like saying "companies are useless and bad" - some companies may be useless and bad, but you'd need to show an essential reason why the majority must end up that way.

FWIW, I think you're wrong and that unions are good at improving worker conditions and pay, and that's why companies engage in aggressive union-busting and anti-union propaganda to prevent unionisation and broadly keep union membership down.