How do you calculate the "full cost" of having staff on call 24/7, well maintained equipment that's regularly inspected, building inspectors to verify that fire code is being met to keep usage down to sustainable levels, and so on? The full cost isn't $10k in salary and gasoline and foam, it's millions.
My city spends ~$20M/y on the fire department [1] and has ~300 structure fires and ~14k callouts annually [2]. The cost for a marginal fire is definitely not millions; even if you only divide $20M by 300 you get $70k and that ignores the tens of thousands of other calls they take.
Total cost of running the department for a year, divided by the number of callouts. Possibly weight the callout types depending on approximate resources consumed.
Though I am fully in support of just letting the house burn.
These costs still exist in a hypothetical year with zero fires, though. Additionally, people whose house were just on fire with zero insurance are probably not in a good financial position (anymore), and they are unlikely to be able to pay…
If you don't have the money, then a lien is placed on the property and it will be sold to pay the debt. Or you can take out a mortgage to buy it. In any case you'll be richer than if the house is burned down.
Ability to pay still not guaranteed, depending on the financial situation. Family can easily have more that's than assets to their name, preventing collection.
amortize that cost over the population that is covered; perhaps discount the services utilized by residents who pre-pay and charge a premium for those who pay on the spot.
Another problem is the difference between agreeing to pay and ability to pay. Someone might be wiling to pay anything in the moment, but you might be hopelessly unable to actually collect.
