IIUC, that is actually a form of government subsidy, which exists only because there are places that are uninsurable due to flood risk. It is politically unpopular to tell people they have to self-insure because they picked a risky to live. If we decided that were something we were willing to tell people, there'd be no issue with letting the market handle it, same as most insurances.

You mean the same policy that resulted in a whole bunch of people living in flood zones? And which we can't get them to leave because it would be politically unpopular to raise their insurance premiums to reflect their actual risk? That seems more like an example of exactly why we don't want the government -- which inevitably means politicians -- setting insurance rates.

Government provided residential flood insurance is a horrible example of moral hazard and should be eliminated. Taxpayers shouldn't have to subsidize investors who choose to purchase property in flood zones.