"I'm not sure I'd want to doctor Wal-mart employees at the rate Wal-mart would want to reimburse me."
The Doc would not be in a business relationship but rather an employee. Thus no negotiations of price per unit cost. The Mid level practitioners would be under the Doc in the local area. If this is placed in tandem with a traumatic event policy it would work in a far more cheaper manner.
The biggest problem in health care is all the little piggies that want part of the dollar. Five piggies wanting a dime each kills the purchasing power of the health care dollar. A doc would have a great job with a great retirement package and stock bennies. The midlevels would be correctly used and the local ER would have better cost recovery by not be burdened by the ones who wait too long or will never pay.
Maybe this would make it a little more clear: Wal-Mart is infamous for squeezing costs out of everything associated with their business. They squeeze suppliers for cost reductions as relentlessly as any business in America - that's my guess. Employees are relatively low paid, but perhaps make what they're worth. Etc., etc.
So I just think that, regardless of how exactly they went about hiring a doctor or contracting with an independent doctor, they would end up squeezing the doc for near subsistence pay (for a doctor). Whereby he might make several times as much money not being a direct employee of Wal-Mart.