However, my dad is a union employee - he works on elevators. It's a small union, and it doesn't have a bunch of 'no penalization' bullshit, and no seniority promotion clauses. The benefit it offers are a standardized health care package, so he can keep the same healthcare and retirement regardless of employer (there are only a few elevator companies anyway). The union also guarantees overtime. He can still get canned if he starts skipping work, doesn't perform etc, it just takes legitimate documentation to have happen.
There are upsides and downsides, but I believe a well run union is a good thing, but in general unions are not well run and are in actuality, terrible for the private sector.
I used to think this way; even having grown up in and around Detroit. But it only takes a few years of actually paying attention to continued corporate abuse of employees -- numerous cases of flagrant violations of labor law and regulations -- to realize that's completely wrong.
All unions are not the UAW or Teamsters any more than all companies are Enron and Merrill Lynch.
All but your very last example[1] are unionized public employees. They work for you and me, the taxpayer. I can't even begin to comprehend how unions in this sector have ever been a benefit to the economy or the public.
I find it outrageous that it was ever allowed to happen, since, evidenced by your own viewpoint and conclusion, it has utterly eroded what unionization stands for.
I agree that unionized industrial labor was a good idea in 1900. I don't think unionized public employees were ever a good idea. Isn't this kind of corruption the stuff of revolutions? "Taxation without representation" is what it appears to amount to.
In the private sector, unions might still make sense as a hedge against corporate exploitation of workers, as other commentors have pointed out. They also might not. Your grocery store example I've seen here in the Bay Area, and the market is quite unforgiving to a business with such slim margins.
[1] The automakers are a pretty muddled situation, though the US government now owns enough of GM that I'd consider it little different from the postal service.
Tell that to the workers at Upper Big Branch Mine.
And when the unions inevitably kill their host, they still aren't made to suffer. The federal government steps in and guarantees their pensions and salaries. Imagine what kind of incentives that gives the union leaders in future negotiations. Oh, and union workers will have lower taxes on their health insurance than non-union workers under the Obama health care plan even though union workers make more money on average, just to rub a little salt in the wound.
In 1900, unions were a great idea. Now they are poison.