I hear what you’re saying for sure!
This is going to be a TLDR post and I’m going down the rabbit hole, but here goes. As small communities served by volunteers grow bigger and bigger, the fire departments struggle more and more to turn out adequate staffing to many calls. Town fathers start questioning things. Turf battles occur. Finally, after a horrific fire, the choice is made to supplement the volunteers. Turf battles still occur and grumblings are heard. Other surrounding towns start experiencing similar problems. They, too, hire career staff to supplement the volunteers. Soon there are ten towns in a county (think suburbs around a city) that all have a mix of career and volunteer staff. Much duplication occurs and there are still turf battles. Then someone gets an idea… “let’s create a county fire department!”. So a county fire department is created under one fire chief with more streamlined operations and coordination. But that’s not the end of the story. As some of these towns grow bigger and bigger and, in essence, become their own cities, they realize they can create their own fire department (perhaps that’s what’s happening in South Florida). Maybe 7 of the original 10 towns end up with their own fire department and the other 7 towns stay with the county fire department. Summing up, the only thing that will eventually break any system is total inefficiency, as in, there were 3 major fires in town last year and each time our volunteer fire department turned out with 6 guys! I’d bet most residents would demand change before the whole town burned down. Of course you’ll always have few a diehards who will fight it to the end!
But within our lifetimes, there will still be small town, rural America where hiring full-time firefighters is just not financially feasible because of the minimal tax base. To handle their 200 calls a year, those small towns, villages, and hamlets will still depend on volunteers.