This is awesome. Can you think of any major downsides to an approach like the German system takes?
It also means that in a bid to save money, self-employed people pick an option that's cheaper now (private), but will cost them a lot more over time, with no option to switch back.
Normally, if you switch to private, you must stay on private. This prevents people from getting cheap private insurance when they're young, and cheap public insurance when they're old. In practice, you can just get a low income job for a year at age 50, and get forced back onto the cheaper public system. It's a solid financial decision.
The same thing ultimately happens here where the young and healthy leave the public pool, leaving the older and sick. As rates go up, the cycle continues.
I don’t see how anything except a $0 for everyone really works. Otherwise you just have people gaming the system (like the 50 year old in your example working a year of low paying job to qualify)