Holy shit dude, have you used one?
Please place item in bagging area. Are you using your own bags? [Yes]. Please wait for staff member to come over and give you permission to use your own bags. Would you like a receipt? [No]. Please take this 30 centimetre long piece of receipt paper that isn't a receipt, it's just printed with stuff you don't want.
I don't think it's justified getting all upset about a few comments, but if I saw an article about someone getting arrested for smashing a self-checkout machine then I'd assume the machine probably deserved it.