Banker would simply not lend to random anyone he doesn't trust, just as in real word.
And when the customer deposit rebate points - trust grows.
All rebate points expire 1-year after their date of collection.
The reason why it will work even in worst case.
The answer to 1984 is 1973 § Panasonic or Samsung - that is the question: Whether 'tis nobler in the mind to suffer.