By quality do you mean coverage?

I think the issue described in the question above becomes a coverage issue. The quality mentioned is based on the "quality" of coverage you have. People with more comprehensive coverage are sometimes given test/treatments that may not be necessary, but since it is "covered" they don't see any reason not to provide these services. On the other hand, people with coverage that is not as comprehensive have to pay out of pocket expenses to obtain the same test/treatments that may actually be necessary for their course of treatment. I don't think that this issue can be simply addressed. There are to many factors that affect quality in this respect. I think good quality of care is defined as comprehensive care that includes all and any test/treatments that are needed to maintain and improve one's health.