Already Happens to a certain extent. My father has a government job and because of that our family gets cashless treatment is hospitals, the government pays for any and all treatment even in private hospitals. Plus any medicine we buy is later reimbursed by attaching the bill.

So yeah Doctors often write unnecessary tests, they tell us to our face You have a cashless panel so just go along with it. Also Pharmacy Shops that usually offer 20% discount on the price will agree to make a Bill of full price but give us a discount either way. So suppose we buy Medicine worth 10,000, we'll pay the Pharmacy guy 8,000 he'll give us a bill of 10,000 and we'll claim that from the government. Profiting by 2,000