Well, scratching my head over the "in network" and "out of network" doctors. As far as I know, with a medicare "supplement" you can go to any doctor you want to ...assuming they take medicare patients of course. We tend toward specialists...like we have a cardiologist who is basically our primary doc - as he does the intensive blood work and testing. I'm not understanding what an "out of network" doctor would be, maybe someone else here can explain, unless its a term pertaining specifically to certain "advantage plans"?
You are correct. With Original Medicare you can see any doctor that accepts it. So I guess you could say Medicare is a network plan in that respect, although the network is huge. A PPO will allow you to see doctors who are in network and at a (much) higher price those who will accept payment but not the PPO's limiting charges - hence out of network.
HMO plans have limited networks and with a few exceptions require approval to see specialists. Most contract with medical groups. A few (like Kaiser) are "staff models" meaning they are both the insurance company and the medical group. Many people love Kaiser because everything is under one roof. If you don't like Dr. Kaiser you can see a different Dr. Kaiser. And just to clarify, Kaiser is NOT non-profit, they are not for profit. There is a difference. With not for profit there is no way to know how much money they make.
I know many people who love HMO plans and have probably enrolled over 1,000 people over the years. Fortunately (for the time being) we have a choice in how we receive our healthcare. It should be up to the patient to make the decision that they prefer. You and I have chosen Medicare and a Supplement. Others like a Medicare Advantage Plan, either PPO or HMO. And I'm good with all of this. Nobody should be forced into a "cookie cutter" plan.