The mayor of the town said the fire department couldn't stay in business if they allowed people to pay "on the spot" for their fire coverage. Assuming he's right, then saving houses in the manner you're asking them to would result in the firemen losing THEIR houses.

Businesses have a duty, first and foremost, to their employees. If they have extra resources and are able to act charitably, that's great. This business did not, and could not.

I don't believe it's a reasonable moral expectation for people to ruin themselves to help others. It's heroic and amazing when people do, but it's not a reasonable expectation. If you disagree, then by all means, call the people up and pay for their home repairs, even if that'll get you evicted.