The German system requires every one to be a member of sickness funds.
These are non profit organisations which provide healthcare for their members and have to take everyone. People are free to change funds at any time.

It used to be that Germany allowed the very rich to opt out of the system and could buy private insurance if they wished. However they must now buy insurance (a mandate).

The cost of insuring children, and the unemployed is met by the state, with the cost of care for everyone else split between the employer and the employee. Premiums are based on a percentage of a person’s income.

There are no networks, and minimal charges for services. Basically the Germans have a set of rules for what they will pay for and how much.