Bank and vulnerable passwords

There is a bank which gives their customers a password 'only' for transactions(there is no username) via ATM. Also the ATM does not have any enter key, it automatically logs you into your account as soon as you enter the right password. There is a huge problem in such type of system,i.e., suppose that if two people A and B have “aadil” and “aadilahmad” as their passwords respectively, so whenever