I work for one of the largest ambulance services in the country and we are private. We run well over 60,000 calls every year. This is mainly because we are the premier service in the county, thus making many of the small, volunteer ones "obsolete". People subscribe to our service and the volunteer services never make it out of the gate.
My thoughts on the private service are fairly positive. We offer acceptable membership fees that allow patients to get quality care w/o a large bill. Our system has a very respectable on-scene time. Also, we train all our own EMT and Medics. However, we do have a few negative aspects. One is we run many transfers and do not utilize our BLS crews properly. Another aspect is poor pay of the employees. We have approximately 200 EMTs and 100 Medics. The pay difference between the two is minimal.
In the long run though it comes down to quality patient care. I can say for certain that our staff is trained well (though some do not exhibit it) and we receive few complaints from patients, families, or healthcare providers in hospitals.
Just my observations!
dxu