Well, think about it... What is the balance of your checking account. No, don't get online to check. Jsut tell me.you wrote:But Bitom! There's no spot for Credit balance on my sheet!
You don't know, do you? Not down to the penny.
And you don't even live in a totalitarian state run by an insane computer that processes thousands of minor fines and bonuses per second.
You know when you check your balance, so does your character.
Unlike your character, you can count on your balance being the same when you check it tomorrow if you don't spend any money. Life in Alpha complex isn't that simple. So it's really easier just to swipe your ME card and hope it's not denied.