Uh, what's the transmission mechanism for this?

It's true that the National Flood Insurance Program does this, but that's only for flooding (which, admittedly, is a big part of hurricane damage...). Flood coverage is however not a standard rider on homeowner's insurance policy products, and I'm also unsure whether it can ever be. I've only ever seen it offered as an additional policy product.

The concern over pricing below the actuarially fair value is well-placed[0], but I'd urge being precise.

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0: https://home.treasury.gov/news/press-releases/hp548