Of course single unions can very well suck and corruption is a problem in any human institution. Furthermore a union for a small group of workers at a critical and fragile position in production (over here it is e.g. air traffic controllers) can exploit their power to bargain for wages above productivity.
But this doesn't imply that unions in general suck and basically steal from their members. That's just a false generalization based upon the bad experiences of your father. I also don't appreciate the symmetry you imply in your last line, as I pointed out above the union memberships ratio has steadily declined while corporate power has obviously increased. I rather worry about corporations destroying our democracy, our free markets and our ecosphere than about a few bad or corrupt union leaders.