Yes, providers. Not even the corporate monster healthcare companies. Individual providers and group practices. Medicare and Medicaid doesn’t even collect co-pays on most encounters; when a patient never gets a bill, a practice can bill for procedures/visits that never even happened.
Upcoding is a lot more common at point of care. I used to investigate fraud, waste, and abuse for my state as a contractor and then a state employee. There is tremendous fraud, but almost none of it comes from recipients. Large corps I would look at things like durable medical equipment.
I was on Medicaid in 2018, a physical therapy practice in Anchorage was apparently billing for services through 2021 even though I had stopped there in 2019. I don’t understand why people think individuals collect money from Medicaid, like you say, services are billed .
It’s the false narrative the politicians use to take benefits away from people. They want that money. Doesn’t go to them directly, but they are paid otherwise. Lot of hinky stuff happens with political appointees too. Good luck getting anyone to pursue it though.