> Assuming that was under the deductible, so the ambulance provider did not get paid anything else
Hm? The insurer would've paid the difference (minus some additional discounts depending on the size of the insurer and its bargaining power). That the patient paid $500 does not in the slightest bit indicate that the insurer negotiated the rate down to that pricepoint.
Even at $500 (and let's assume that was an hour-long ride, for easy math that's maximally generous to your argument), EMTs on average make around $20/hour at best, and maybe double that for a nurse - so a fully staffed ambulance would run around $80/hour for labor. Round it up to $100 to be generous and that still leaves $400 for the ambulance itself. Ambulance itself costs up to $150,000, so earmarking another $100 would pay it off after 1,500 hours of service - so less than a year, even if it's only running for 40 hours a week. Maybe it's really fuel-inefficient and breaks down frequently, so we'll say another $100 for fuel and maintenance. Throw in another $100 to pay off $150,000 worth of equipment and medical supplies.
So of that $500 price the patient pays, we're left with $100. At the price billed to the insurer, that's an eye-watering $11,600 of what appears to be pure profit. Maybe there's some excuse for that, but to me it's pretty obvious that something's way out of whack. $500 or even a bit more than that would be reasonable if EMTs and nurses were being paid better, but they largely ain't.