Why should health insurance be progressive? I'd be willing to bet that healthcare costs scale sub-linearly with income, so why would a private insurer charge more to somebody who makes more money?
In the case of a properly functioning public healthcare system, I totally buy and support it, though.
Good question, but I'm not opposed to this. I'd say the German health care system is mostly a good one, and I'm absolutely happy to pay a percentage of income. Sure, if they managed to have it running at a flat fee that doesn't disadvantage people with minimum wage jobs, I'd gladly pay less - although I think 10% is totally fair, especially when comparing it to the US system and people doing kickstarters for their cancer treatment...
I actually agree with you, for a system run as a public service (which I think healthcare should be), I just don't see a workable justification for it under a private system.
The difference is, I think, in the word "insurance". If a USAn doesn't pay for health insurance, they have to pay for healthcare. I don't particularly know how Germany's system works, but I'd assume that non-payment of taxes, while it probably has other repercussions, does not preclude receiving healthcare.
My complete guess would be that this is an intra-union agreement. The insurer could be charging a fixed rate per member with the union enforcing a progressive scheme.
In the case of a properly functioning public healthcare system, I totally buy and support it, though.