In my industry, union labor was paid significantly more than management, but likewise, management pay had to at least be relevant. There even was a time when some management teams tried to organize. Everyone got a pay raise and those leading the union effort all got fired.
I'm not against good pay for blue collar work, although I would like to tie it to good ol' supply and demand, not union bullying where the good, the bad and the ugly is all protected the same.
My gripe is with what I see as a cancer in a business organization. Wrestle hire/fire from management, and force bargaining on anything that's not agreed upon in the contract, which effectively means freezing operations to a standard.
I strongly believe that elected government should set the detailed rules on employment that are clear and apply to all, in which case there would be no need for unions. Businesses must have the flexibility to hire and fire based on need and competence, and management should always be in charge of guiding the ship forward, not the mechanic in the engine room.