Credit cards are issued at 10%-30% interest rates. This is the norm for unsecured debt; to get a decent rate a debt must usually be backed by something. Mortgages have the lowest rates seen with consumer debt because even in foreclosure, the house can (in normal economic conditions) be sold to repay the debt in full.

Student loans can't be made at reasonable interest rates without either a strong guarantee of repayment or a taxpayer subsidy for the risk. The current system has a bit of both.