How does anyone imagine that the government can “keep insurance companies honest” and to make sure everyone gets coverage, when medicare is currently leaving sick and dying old people out in the cold almost three times more often than the best private insurance companies?
If you take a look at the report card, you'll see that the denial number include people asking for co-pay and deductible amounts, so the adjusted Medicare denial rate will be higher.
From the American Medical Association's 2008 National Health Insurer Report Card.