That's a form over substance argument, and these are always losers in court. The smart concierge players don't bill insurance companies, period. Not ever. You simply tell your patients that they have to forego their insurance if you want to use them. There isnt a legal way around this in most jurisdictions, and never with medicare or medicaid. The guys that try to play fast and loose with the insurance laws, taking both cash and insurance, are just waiting to get caught, I'm afraid. Again, this limit on customers is the big reason everyone doesn't do a concierge business -- the pool of potential customers is simply very small.
Are you sure? Take a look at MDVIP, a larger player. My understanding is that a bunch of groups a) accept insurance and medicare and b) charge a retainer for the services they provide that, in theory, are not covered by insurance. Bear with me, since I have no legal background (although I do have a business background). But it seems to me that your argument applies to something like the following: a patient comes in for a blood test, the practice bills the patient for the blood test, and bills the patient's insurance for the blood test. This obviously sounds fraudulent.
On the other hand, I can't see how your argument applies to this case: a patient comes in for a blood test, and the practice bills the patient's insurance for the blood test. The practice then bills the patient a fixed annual retainer that specifically states that this fee is unrelated to the blood test. The same patient might get ten blood tests, his insurance then billed for ten blood tests, but the retainer would not change. I believe this is how the majority of concierge practices operate.
Now what if concierge practices used a business model that billed the patient for hours of work plus retainer, and then billed insurance for the procedure? I think it would be easier to make a legal argument against this model, but even still, I'm not sure if it's illegal. On the other hand, since retainer plus insurance and retainer plus cash-only are the dominant models out there, I don't think many patients would agree to retainer plus billable hours plus insurance.
But like I said, take a look at MDVIP - it's a big network with serious financial backers. Do you know of any specific rulings that say such a model is illegal? I'm not asking rhetorically, I just haven't looked into it myself very much. And again, like I said, concierge medicine isn't something I'd be able to do myself, but I'm just curious about the implications surrounding the model.