Historically, the private insurance market didn’t insure floods because all the houses flood at the same time, and the company wouldn’t be able to pay.
Insurance works by spreading the risk. Everyone pays premium, and those people who have bad luck get reimbursed. And for fire (originally the only insured loss on homes – it was called fire insurance, in fact) that model works well. Back when most insurance companies were small and regional, the risk of flood was simply impossible to insure by the private market. That’s why, when homeowners policies became more comprehensive, covering more than just fire, flood damage was excluded.
The federal government picked up the slack, because it was large enough to accept the risk of flood in one area. But it has underpriced the product for years (in part because it can tax all of us to make up the shortfall). But as a result, even though there are now large international insurance companies that probably could insure flood, no private company is interested. What private company wants to sell a coverage at a loss? And of course, the regional companies still couldn’t do it.
(Actually, there’s now this thing called reinsurance, and if flood coverage was, on average, profitable, regionals could spread the risk to larger companies and it might work.)
But even though the federal government sells flood insurance at a loss, many home owners don’t buy it. I’ve heard that only about 20% of the homeowners in Houston who were eligible to buy it (live in flood-prone areas) chose to do so. That’s because even though it’s subsidized, it’s very expensive.
Which goes back to the point above, that many homes are built in places where there shouldn’t be homes, because the risk of flooding is so high. Flood plains would be better used for things that require less expensive infrastructure. If you lose your rice crop every ten years, you can easily replant the following year, and if the land is fertile from regular flooding, that might make economic sense. But cheap flood insurance has encouraged rebuilding in-place.
I think North Carolina, which gets a lot of hurricanes, doesn’t allow rebuilding of homes lost to hurricane flooding, at least in the most storm-prone coastal areas… You can get your insurance money, but you have to find a new place to live.
The federal flood insurance program is expiring, and up for renewal. I’m sure this storm will affect the conversion in Congress.