I bet the banks lose money on credit cards in EU. They are loaning out money up to 60 days for only a 0.3% fee. Interchange is meant to cover these loans.
(A) Yes, in many countries. (B) that card loan is only at effective 1.6% for 60 days; if it’s not paid at that point it turns into potentially 20%. (c) Most card payments are debit anyway afaik; no loan longer than a day or so involved.