Simplifying slightly, the way consumer credit works is, if you expect 10% of your customers to default then you need to change 10% interest to even break even, let alone cover your administrative costs, and let alone to make a profit. If you are in a market segment that has somewhere near 30% chance of defaulting then your options are a) a 30% credit card b) no credit at all.
It's not a question of chance of failure but rate of failure. If 10% of your customers failed every 10 years then you could make a lot of money at 10%APR compounded monthly. You can also be extremely profitable with a 3% failure rate per month and 30% interest rate, because you can sell that bad debt for more than 0$.
PS: How it's called an APR when they charge you APR / 12 per month is beyond me.
