Businesses are one thing, but what I find truly dystopic about the idea of 100% cashless societies is that you could off people in the same way.

If today, you lose access to your bank account for whatever reason, you still have various options how to purchase necessities: If you got some spare cash, you could use that; otherwise you could ask a friend to lend you some cash.

In a cashless society, that won't work: Even if the friend wants to help you, they have nothing to wire the cash to. They'd literally have to buy the individual goods for you.

The only way to fix this would be to get a new temporary bank account until the old one is accessible again. But if you got banned for whatever reason, chances are the bank will ban the new account as well.