Actually, i don't think think there is a shortage of primary care providers in the country--at least not in the urban areas. Shortages in rural areas are due to issues that go with it being a rural area.
There may be shortages for specific insurance plans, but again, that is due to speciifics about the plan (can you say "reimbursement"? how about "red tape?")
If all the medicaid patients cannot get appointments, but the commercial patients can, their is an issue with the medicaid plan, not a general shortage of pcps.