Insurance has negative expected value in return for risk pooling.

If something has a high level of importance in your finances or for other reasons, it makes sense to buy insurance. If you can handle the risk yourself (typically because the investment is not a terribly large amount of your total investments, and you do not think risk for this investment is correlated with risk to your other investments), then it doesn't make sense to buy insurance.

House flippers could be anything from very small one-person operations who would be wiped out if they had to clear a lien, to fairly large operations who can absorb the occasional risk into their costs of doing business.

That's fundamentally why title insurance doesn't pay out much. They exclude most defects that aren't discoverable and it's easy for everyone to find the defects that are. They are providing little actual protection hence why they pay out so little of premiums as claims.