> They are selling services without providing prices...

And it takes a state license for them to operate. The state could require them to provide an accurate and up-to-date price menu in order to remain in business.

I think the problem is also related to the opaque negotiated prices that "in network" providers negotiate with insurance companies, driving up the cost for uninsured or "out of network" consumers.

There are perfectly rational solutions short of single-payer.