I know a number of people who belong to an unusual HMO health insurance organization. I don't think that there are too many like this HMO in the U.S. It's organized as a separate entity. They have their own clinics, hospitals, rehab centers, pharmacies, and medical equipment facilities.
The organization has their own doctors, nurses, specialists and surgeons. The doctors treat only the members and members go only in-network. It is a huge organization and members pay a reasonable premium. Most medical services are paid for, but there are a few limitations.
To go to a specialist, you need to get the O.K. from your primary care physician. Most hospital stays and surgeries are taken care of. Prescriptions costs are paid for. It is a complete one-stop medical visit.
One draw-back is you basically have no choice in doctors or treatment. This approach appeals to lots of people as this health program has been successful for over 40 years.