7% of the workforce is in a union... but what percentage of the workforce has to deal with their presence? If union contracts weren't exclusive, how many members would jump ship and leave?
I'm not suggesting that collective bargaining shouldn't be allowed. Quite the contrary; I think it's a necessity. Participation in that collective group, though, I think should be wholly optional. We would indeed find it strange if a town mandated that everyone living within its limits must buy stock in a particular company.
I'm not familiar with Germany's unions specifically. If they're better, that's good. I certainly wouldn't place the blame for America's troubles wholly on the employers, though, or the unions. I see it as a mutual problem... the unions and the companies are both throwing their weight around to undermine each others' power, rather that working together to reach an agreement. Neither will give up anything.