No, they usually do it because back in the day, funeral homes couldn't keep up with federal standards. Or towns just didn't have an ambulance, and nobody wanted to do it; so groups of citizens got together and formed rescue squads, or first aid crews, etc. A lot of good came out of that, it's not all bad, it just depends on how things work in each individual town. Some people have done it, hated it; or got burned out and moved on; or just don't understand how it works. I don't have the patience to explain it.
Anyhoo, people created ambulance services so their towns, no matter how big; or how dinky, were not so far from other services. Or maybe they thought they could do better, than what was already in place.
Today, either municipalities won't foot the bill; or there are so many services, that everyone couldn't go paid because they wouldn't bring in enough cash. If it were planned well, and you replaced every three or four services with two staffed ambulances; it could probably be pull off. But there is no way to make every service paid, they'd go bankrupt too soon after. A few i.e. hundred or thousand; would have to be dissolved. Smaller areas don't need 10 ambo's; larger areas need 20. As many years as EMS has existed, it will take twice as many, to solve all of it's problems.
I believe the solution is consolidation.