Because right now debit card purchases don’t have a transaction fee while credit cards do. I just had two recent purchases where the vendor charged a 3% surcharge for credit cards but would do the transaction by debit card free.
It is an example that greed is everywhere. Not only among card issuers but also among merchants. The moment merchant find a socially accepted way to extract extra they will do it. Similar to tip screens on square terminals in all takeout places. Costs nothing to ask, generates some additional revenue.
