Bpost banque subcontracts to BNP Parabas. Using a paper cheque to get access to cash does not require patronising either of them. You do not pay them a dime and you do not sign a contract. The profitable data they get from the person presenting the cheque is minimal. There is no interesting data to abuse or exfiltrate in a breach.

When you send a bank transfer, the money is in limbo for a period of time. The money leaves the payer’s account and sits in the bank’s own account where the bank earns interest. After some time, the money eventually finally moves into the recipient’s account. That limbo time is quite profitable for the bank. So the bank tries to keep that limbo time as long as legally possible. The bank loves your patronage.

With paper cheques, the money is in the posession of the payer up until the cheque is furnished. At that moment, cash is paid to the recipient. There is no profitable limbo time in this case.