I was going to comment on the loan structure of credit cards earlier, got too long winded, and even political, so I edited it away.

Some people get confused and think credit card providers are a banking service meant to make life easier instead of the loansharking operations which they really are.

If you are paying your cards off on time you are tying up their money and not only not paying interest but depriving them of the interest they would have earned on that money if they invested it somewhere else like a business loan or treasury bond.
So if you are using interest free credit you are actually costing them money out of their pockets.

Of course they would prefer that you didn't do that.
From an accounting viewpoint they would prefer you not to use their card at all if you pay no interest, but because they are hoping to get you hooked into their loan-shark interest rate structure they use free credit card use as sucker bait.

That is the big difference between credit and debit cards. Debit cards only allow access to your own money and are not loans.