The sirens are the key. There are a lot more ambulances on the streets these days for old baby boomers getting sick, exploding homeless population, exploding illegal immigrant population, and exploding poor/welfare population. None of them pay for insurance or worry about the cost of going to the ER because they won't have to pay it anyway. An ambulance is a free ride to the hospital for them.

I doubt the drivers run the sirens for someone going to an appointment at the hospital that didn't have a car or money for a taxi/bus.