Volunteer fire department is basically a 1/2 to 3/4 time job with no pay. For insurance and regulatory reasons the volunteers need to take almost all the training that the regular guys do and that eats up a lot of time. By the time you do your monthly training and then required minimum hours you are putting in ~60-80 hours a month minimum. The only people that can afford to do that either dont sleep or are retired.

On the subject of obesity that's also a huge problem for the volunteers, not only is the pool smaller but the people that need rescuing are bigger... way bigger. My buddy was volunteer EMS and blew out his back rescuing a 300+lb lady. Getting a 300lb person down a set of stairs needs either really expensive equipment or is just a recipe for injury and mostly its just injury since nobody wants to buy expensive stuff.

Realistically through its too expensive to provide services everywhere in the country, there are places that simply do not have enough population density to provide organized emergency services and need to revert to a more rural existence. The missing element there is that small communities are being choked by shitty one size fits all regulation that applies the same standards of training and regulation that exists in larger cities, and areas with higher density and that cant be supported by a community of a couple hundred. Lower standards of training should be fine in smaller communities.