The interest rates charged by credit card companies used to be illegal and usury as well. But the credit card lobbyists became so powerful they got the laws changed.
40 years ago such rates as 20% were given only by loan sharks.
If you knowingly agree to a 20% loan, I have no object--and no sympathy for you. There are reasons you might be willing to do that, including bad credit and urgent expenses.
Where I object is when the creditor breaks your knees for not paying; he's within his rights to offset risk with an agreed-upon rate, but not in violent contract enforcement.
I also object to contracts with deceptive terms, such as: Own a laptop for $30 per month(*)! (*) Payable over a 1,000 year term.
The devil is in the continuum problem: where does negligence on the part of the buyer leave off, and fraud on the part of the seller kick in? Morally, I depart from the libertarians there: when selling to the stupid, I believe there exists a moral responsibility to make darn sure the buyer understands the contract. I'm torn how far that should be enforced by law, though, so I'm sympathetic to the libertarians on that score.