The situation it lays out, where the $100k of other driver's liability coverage isn't enough to cover their damages (including what health "insurance" paid out)

The situation it lays out, where the $100k of other driver's liability coverage isn't enough to cover their damages (including what health "insurance" paid out) - isn't that exactly what the "underinsured driver" line item is for? Also isn't the main reason you never cash such a check from an insurance company is that it's an offer for a final settlement, or at least could be construed as such, even though you might be owed much more? I do agree that it's a problem for insurance companies to be able to set upper limits on coverage, after which they walk away. The whole point of insurance is to cover long tail risk. If the area under the chopped off long tail is really that large, then that means a lot of damages are just currently being dropped on the floor.