You could get the minimum insurance required by law and then dedicate a saving account for when you might need it.
The better argument would have been to say that there are life insurances that you can borrow against, so why not car insurances. I guarantee the reason is because of lack of demand and therefore not profitable. If people were wanting such a thing, someone would provide it, but the reasons for such a policy as well as what the collateral is are two different things.