Supermarket

Why is that every time i queue to pay in the supermarket, I end up in the slowest queue because either (pick one):

• someone before me forgot his credit card, has no cash, and starts a huge fuss
• the credit card terminal stops working
• the roll of paper for the reciepts is empty
• the price for item X is missing, and someone has to go check
• some old lady insists on paying to the exact cent amount by rumaging through her purse for hours, trying to find just the right coins (but she forgot her glasses..), and No thanks, she does not want anyone to help her, she's fine!
• the girl cashing in forgot to remove an alarm from some clothing because she didn't realize instead of the usual 3 beepers, this one had one more, so security is running towards the client and unfortunately, we have to wait..
• ... (add your own)