Landlords typically have insurance coverage for damage by tenants, including lost rent.
This form of insurance is exceeding expensive and exceedingly rare. Large buildings self-insure (by having a ton of doors) and small landlords don't want to pay it.
It’s hard for new landlords. People that bought houses to rent compete against property owners of paid off homes or people with 3% mortgages.
Tacking on optional insurance products on a property that’s already in the red further encourages landlords to push up rents prices.