>They don't create wealth out of nothing.

Banks loans may not create wealth. But they promise its creation to the society. The value of the money that they lend out comes from that promise.

And the people who borrowed from the bank create wealth when they repay their loans. The responsibility of the bank is to track it and ensure that it is created. OR that the money lended out is not spent. Either one should happen when the loan is repayed, so the bank does not care which one.

If the banks does not do it (ensure repayment or collect collateral), then all the people who worked for the money loaned by the bank, got their work stolen.

In other words, when you take a loan from a bank, you are actually borrowing from the society.

So watch your banks very closely.

> But they promise [the creation of wealth] to the society.

It feels like you're trying to describe the "social contract" between private banks and the rest of society, but putting the full responsibility of "wealth creation" only on one party in the contract: The bank.

The other party, Society, is given access to capital when they borrow. The rate they're charged should be competitive since there is presumably more than one lender. By borrowing money they try to "create wealth", then to repay the loan principal along with a bit of the new wealth in the form of interest.