You would think they would require it, but I know plenty that don't.
I insist on it, during the odd times that I actually have an auto loan.
Or if you buy used at or around blue book values, you'd only be out your deductible for a total loss.
If you have your eyes on a particular car, call your insurance company and ask two things:
1) how will owning this prospective vehicle affect my premiums?
2) what book value does the company have for this car given the make/model/year/trim/mileage?
If #2 is way below the street price, either be prepared to keep a cash buffer for the difference, or perhaps you're not finding a fair deal.
If you are a payment or so in the hole, that kind of sucks, but you can survive it. The people who get screwed are those who way over leveraged and also have little cash savings.