I'm surprised at the vitriol poured upon the American car workers union. On one hand it is perfectly reasonable for a company to pay its upper management vast sums of money on the grounds of competitive advantage, and perfectly unreasonable for the workers to form a union to represent their needs.
The truth is that unions and corporations are mirror images of each other. The more monopolistic and powerful the corporations become, the more essential it is for an equal and opposite force to form to balance the system. Without that balance is broken.
Yes, large unions do self serving things, but so do CEOs and boards of directors. It is more accurate to say that all forms of concentrated power can result in abuse (power corrupts, absolute power corrupts absolutely).
I believe that a key technique for improving the situation is to limit the size of unions, and the size of corporations, to say 150 people (the natural social heirachy limit). Groups of these can form into larger groups, but must do all their trading in public.
The reason for such a maximum group size is to limit the power base of individuals to that of a human comprehensible scale. Of course these groups will often need to form larger collaborations, but the interaction must be done on the free market place to prevent monopolies of money (as we see with large corporations) or monopolies of labour (as we see with large unions).
To throw out unions is to revert to the early industrial era, with its slave level wages and terrible safety.