I completely agree. I thought this only yesterday, when I went to the corner shop with my 13yo DS after school. I saw a girl of a similar age come in and she was immediately scanning the shop. I wondered why, then I realised that she was looking to see if she was allowed in, on account of how many other kids were already in the shop; even though she'd actually gone in with her mum.
As somebody who would never have countenanced thinking of stealing from a shop when I was a child, and as a parent of a child who is the same, it's horrible to be tarred with the same brush. Meanwhile, a group of adults could go in, with one/more/all of them happening to be thieves, and they're free to go on right ahead.
I thought the same as you regarding if it were based on ethnicity instead. The racism involved in police routinely pulling over young black people who have nice cars, with the assumption that they've likely stolen them. If called to account, they will splutter that young black people DO steal cars. Yes, indeed some of them do; just like some white people and some older people of all races. But the vast majority don't.
It's horrible and lazy to blatantly discriminate against people in this way. If they're experiencing non-payers, they would be better to just change their official policy so that everybody pays when they have the drinks. What great benefit does it actually bring to charge them later? It just sounds like an extra unnecessary admin task for the staff and for the customers to have to remember; isn't it much simpler to order the drinks, pay for the drinks, drink the drinks, all dealt with?
I don't think it's the same as insurance, as the whole idea of insurance is spreading risk across a much wider group. It's one thing to say that you're young, and younger people on the whole tend to have more accidents, so you have to pay more than older people do. That's largely based on driving experience - it's a bit difficult to have been driving for 30 years when you're only 19 - and, crucially, most accidents aren't caused as a result of somebody's deliberate choice to commit a crime. Obviously claims for theft are, but that's down to an as-yet-unknown stranger's criminal intent and not the customer.