A "credit" is a plus -- a "debit" is a minus.
How come credit cards, which put us in debt, are called "credit cards", as if we're spending some kind of overage we have set aside?
Meanwhile, "debit cards" sound bad -- a debit is a negative on your balance sheet. Debit and Debt come from the same Latin word. Yet when you use a Debit Card, you're actually paying with money you already have.
Do you think it's a coincidence that those names were chosen? I think not.