Many of my friends even went as far as using that as a method to handle their personal finance as students.

Transfer most of the money to the savings account and then when getting declined buying food top up the card account and rely on it instantly being available. Having negative trigger each time going above the pre-planned spending for the month.

Hell, I still do it. I have one card for groceries which gives me a mental picture of how much I have spent on food given what day it is when it gets declined each month.

I would presume this comes from being the generation that grew up only knowing about debit cards. Most got a personal one at the age of 13 or so and never really used cash. Guessing it is even earlier today.

Didn't get a credit card until first time I was planning to rent a car when travelling knowing how much easier it would be.