Because banks are tired of loaning money to people that won't pay it back on time or at all. That sets in the interest rate for everybody else and makes it harder to build up credit (proof to banks that you can pay when you say you can pay). And, either you're buying a vehicle that costs a fortune so that it lasts a while or you're buying a vehicle that is cheap because the dealer knows it won't last much longer but wants the money for it.