The special power is the banking license they get from the government. Try to do it without and you'll find yourself in prison quite soon. Especially if you do it in official currency.
No, I don't need a banking license to loan my friend $10.
The difference is that licensed and regulated banks can scale it. Retail customers can trust them due to their long-standing reputation, their banking licence and linked to that, the FDIC insurance.
Yes, but this only grants the ability to scale it, not the ability to do it.
We don't say that only licensed restaurants can cook food.