The German system is fun, because while we call one part "public" (rather gesetzlich in German, which describes it much better) and private. Thing is, even the public (gesetzlich) part is run by private companies, they just have to offer a stanrdadized, regulated product at a set and regulated cost, they can offer additional services on top, they can even charge a couple of bucks more. They cannot decline anyone so (exept fringe cases like freelance artists for example, or others with their own profesion-based models) or exclude prexisting condition. Private providers can do that, that's why it is potentially cheaper when being young, but can be quite costsly when people get older. Which is the reason why I always stayed in the public model, less hassle overall.