[Joel says the lesson to be learned from Hurricane Katrina is "you're on your own"--and says "Solve your own problems" is "RULE ONE" at his house.]
"Don't wait for the cavalry"--if you are a pioneer who has voluntarily taken your family into hostile Indian territory, you better take enough guns to defend your wagon. You can't assume that the Army will show up whenever you need them.
If, on the other hand, you are a taxpayer, living in a modern American city, it is very reasonable to expect that in the case of an emergency the FEDERAL EMERGENCY MANAGEMENT AGENCY will have a plan that takes into account various aspects of the situation, such as the high percentage of poor people in the city, and the probability that some people will need assistance to evacuate (like, people in hospitals and nursing homes, AND people who have no car or money and no experience outside their neighborhoods.) That is what FEMA is for. That is what government is for. Government exists to facilitate collective action, to do things that individuals cannot do.
The analogy of parents and children also does not apply. If you die before your children are old enough to take care of themselves, someone else will take over the job--if no friends or relatives step up, the government will do it (badly, probably, but nevertheless, there is a system in place). Your kids won't be on their own until you have had a chance to teach them how to be adults, and at that point, they will be equipped to live independently. The government is not our parent. The government is THE PEOPLE, working together to help each other, and thus, ourselves.