Honestly, schemes like this tend to have big bad consequences.

Force credit cards to charge only 10% interest and immediately many people will lose access to credit cards altogether, or alternatively will have to pay high annual fees regardless of their responsible use of credit, or will have tiny credit limits, or will have to provide their credit card company with the full dollar amount of their credit card prior to being given one. A final effect could be the poor who are affected going to super high interest lenders like payday loans or in the event that even those loans are regulated, even organized crime.

The problem is that unsecured credit lines like credit cards are the most likely forms of debt to be defaulted on, and if banks can’t recoup those losses, then they won’t provide the product. People can blame capitalism for this, but ultimately a similar kind of government program would need to be similarly limited lest the program just become a free money pit as many poor people assume credit cards are.

Now maybe that’s the point, and we want fewer people in less debt, and to force them to live within their means. I’m not necessarily opposed to the idea, but you can’t just do it. You’d have to change the banking and monetary system (for the better). You literally can’t have the current monetary system without debt.