Some are downright dishonest, some are offering products that really don't stand up when you put a spotlight on them. If not, contacting the card company to be sure the cards are authorized. Beware of 'debt suspension' offers.
Banks can offer it without having to use insurance companies.
It is commonly offered as an extra with your card, and is generally sold as a way to keep your head above water if you can't make monthly payments because of a job loss or disability. But this sort of 'insurance' does not do anything to pay your bills while you can't - it simply puts them on hold. While you are out of work you can't use your card, and while interest is not being applied, the total balance is waiting the minute you get back to work. Beware of buying credit protection you don't need. For example, many people have been duped into buying protection in case their card is stolen and the thief runs up a big bill.