Early fire departments were run by insurance companies to fight fires on their customers' properties. Those who couldn't afford insurance would be left to burn.
Ancient Rome had a fire brigade, run by Marcus Licinius Crassus, who you might remember as the villain from the 1960s Spartacus film. He and his crew would arrive at the scene of a fire to save your home from going up in flames...if you sold it to him.
I didn't know about this and it's quite interesting. But I wonder why it no longer exists this way? Is there a reason why a "for-profit" discontinued a service like this?
EDIT: Seems I found a clue ....
"In 1862 insurance companies told the government that they were unwilling to be responsible for London’s fire protection as the cost of compensation was becoming too high. The government decided that the Metropolitan Board of Works would take control."
It's also worth remembering that fires spread. If the house two doors down is on fire you better hope they and the house next door have insurance (and remembered to pay the bill this month).
You hit the nail on the head which naive interpretations of libertarian isolationism often miss -- unchecked problems spread viz fire, pollution, garbage, disease outbreaks, crime and poverty.
As one's liver combats the effects of pollution in your bloodstream by filtering it, so, as a society, we have developed certain organs to combat the degrading effects of similar sorts of problems.
http://www.london-fire.gov.uk/FireMarksAndPayments.asp