some loo roll is priced per sheet and some per roll for example.
I always remember seeing the little price comparison shelf label in Tesco and it gave the price 'per sht'. I was actually quite relieved (no pun intended) when I realised they were abbreviating 'per sheet' 
Ahh remember penny sweets? I used to love picking out a 100 sweets for a pound and watching the cashier count them (and making you put some back if over !)
We had the opposite at our corner shop - they had a tray of about 8 different penny sweets on the counter and if you spent, say 95p, on whatever goods and handed over a pound coin/note, the man would give you your change in random penny sweets - cheeky beggar!
It was a fudge company, which also sells pick and mix. The Great British Fudge Company. The point still stands that a massive concession in a double-decker bus at a rip-off event like a winter wonderland is obviously not comparable in price to sweets bought at Tesco. It’s not about handmade fudge vs mass-produced, or handmade pick and mix vs mass-produced: it’s about where they bought it.
Yes, I think that's what it comes down to. The kids may well not have appreciated that, but the parents should have done - and guided accordingly. Just the same as buying a 'gift' pencil from an attraction gift shop is not going to cost anywhere near the equivalent of one in a pack of 10 from Wilko, you have to go into these places expecting them to try to rinse you at every turn. I'm not saying it's right, but it's the way it is. The fudge company will also have paid a great deal for their pitch fee, which has to be earned back somehow.
I assume their main line is selling posh fudge at prices that people will not expect to be cheap, but they probably also have some child-friendly options, for those kids who don't like fudge (and may otherwise moan and stop their parents from buying more fudge) - like when mid-market foreign-cuisine restaurants also offer burgers and chips for fussy eaters, so that one person with a very limited palate doesn't stop the rest of the group from choosing to eat there by whining "But I don't liiiiike it!". You're clearly going to pay a big premium if you just use it as a generic supermarket '£4 for a massive cup' Candy King alternative.
Whether or not their fudge/sweets are worth that is debatable, but the price is clearly marked and scales are available. Nobody is forcing anybody to buy from them - and it's a bit of a parenting red flag that the kids not only chose humungous, heavy bags of sweets, but they couldn't even wait until dad had paid before starting to scoff them. Assuming they weren't after freebies, and that all selected sweets were duly weighed, I can't believe there was a very long window between the sweets' being presented and the cashier announcing the price, for the kids to grab them and start fisting them into their gaping maws.
We have an amazing chocolate shop near us, where all chocs are hand-made, using proper thick Belgian chocolate and quality ingredients (e.g. proper red juice from actual strawberries as opposed to dry white artificially-flavoured powder like in cheap ones). They are delicious and you only need one for the taste to linger in your mouth for quite some time. We don't go that often, because they are obviously a treat and not an everyday bulk purchase. Their prices per 100g are clearly displayed and they even tell you approximately how many you will get for how many grams; but every time we go, we always encounter somebody who goes in and then storms right back out - with a disgusted look on their faces - because they were clearly expecting these handmade delights to cost a tiny fraction more than a big waxy glomp of Cadburys. Some people really do have highly unrealistic expectations.