I think there is a distinction necessary here. As the Ambulance giant (AMR) has been known to say (at least in my region), there is no money in 911. The real money in the "ambulance industry" is in transfers (discharge, IFT, dialysis, etc). Rates are set by the government, and the billing is just about guarenteed for companies.
In the case of 911, money is harder to come by. My sense is that patients often dont have insurance, or incomplete information is gathered by the crew, making it hard to bill. Even if a company bills, they are likely not to be reimbursed anything close to what they bill. One rural FF/EMS department I know became an ILS service so they could bill ALS-1, but then ste a strict policy to avoid being accused of starting IVs just for the billing. Within 6 months, they had made enough extra $$ to reimburse their crews for the I class, and send two more. The Ambulance started making profit, which, because it was a part of the fire department, was unable to put back into EMS, the money ended up buying new fire toys.
Its a delicate balance...
