1) Trolleys: Supermarkets never have the type of trolley you want, although there are always plenty of trolleys available for disabled mothers with twins. All available trolleys are now chained together outside the store, partly to stop 13 year-olds appropriating one for a joy ride, but more importantly just to really annoy you when you realise you've not got a pound coin in your pocket.
2) Packaging: Supermarkets insist on wrapping everything in packaging we don't want, and then charging extra for it. Why? Because we're mug enough to pay for it, that's why. We could buy real potatoes, complete with organic dirt and real skin, but instead it's so much easier to buy ready cooked mashed potatoes with a sprig of parsley in a cellophane wrapper for ten times the price. It may cut down on preparation time, but it's odd how it never tastes quite as good.
3) Checkouts: I always manage to pick the checkout with what appears to be the shortest queue, but which then turns out to be the longest. The person in front of me in the queue always seems to have managed to buy the only packet of cereal in the shop without a barcode, a pint of milk that's leaking everywhere and a vegetable that the rookie till operator can't decide whether it's an aubergine or a very large plum. Then they produce every money-off voucher under the sun from their wallet, only to be told that most of them are unusable, before insisting on paying by credit card even though the bill is less than £5. Of course, when it's my turn at the checkout, the operator speeds up and whizzes everything down the belt before I've managed to get even one plastic bag open, at which point everyone waiting in the queue glares at me, just as I was doing earlier.