Why do you think the salaries will drop? Can you prove it? I have no problem with minimum wage of $6. But after that the market will decide. The wages won't drop simply because nobody will be willing to work for lower wages.
As for the worker's salaries. Maybe because the different occupations now command better salaries than 30 years ago. And not the case with the union workers. Tell me, should a port crane operator be paid $140K a year? Is it fair salary when someone doing the same kind of work is making 3 times less? Is it normal? Is it fair?