Yes, many doctors are not taking new Medicare patients. If you look at the pitiful amounts they pay on claims, and the fact that some claims are not paid for 9-12 months, you can see how good docs with an established practice would choose not to participate.
Case in point, I just received a statement from a doctor for a procedure for which he billed $497.00.
Medicare discounted it by $329.24, paid $133.66.
My secondary insurance paid $17.05.
My balance $17.05.
So, for a $497 procedure paid thru Medicare, doctor receives $150.76.
Hard to keep the doors open on that.
In my experience, the waiting rooms are pretty full when I go there, so I guess they depend on volume. When I got my medicare advantage plan, I checked to see if my important doctors were in their plan. If you have an advantage plan you can switch during the 6 weeks or so beginning in October to another plan that suits you better.