This could be discouraged with reputation mechanism but it seems that the app encourages creating a new identity for every order, which impedes establishing reputation.

I am realizing that a taker/scammer could take an order and use the code to withdraw the money from an ATM right before providing the code to the maker. It would be difficult to prove the scam because the taker could show proof from his bank that the money was withdrawn. It seems especially risky with orders of round figures in PLN that can be withdrawn at the ATM. Is there any way to prevent this kind of scam?