Went to a fete today. DS (3.5) went on a bouncy castle slide thing.
We paid, and he came down it once, all smiles, then ran round the back again. He didn't appear again for ages, so I went round the back to see if he needed help.
I wasn't prepared for the absolute carnage that I saw! There were about 20 children trying to get up the two ladders. The ladders were both quite difficult to manage and many of the children were struggling. It was pandemonium! DCs of all ages were pushing each other out of the way, falling down, trampling other DCs. One toddler (maybe 2.5 or 3) in particular kept getting knocked back and pushed off the slide, and fallen on by older DCs. I was worried his neck was going to get hurt. Another mum turned up and between us we restored some sanity, picked the little ones up, told them not to push each other, helped them up the ladders.
I found the young guy we'd paid (£1.80) and said there should be someone round the back to supervise. He said that there was a guy, but he was away right now. I said it was dangerous, he went and got him (the boss I think). I told him that it had been getting dangerous. He said "there's no blood, it's all fine" 
10 minutes later, the "boss" was off round the front again, chatting on his mobile. A little boy was struggling at the top, his dad was standing on the bottom of the bouncy castle to give him a hand up. When the boss came back, he had a go at the guy for standing on the bouncy castle. He said "I was helping my son". The "boss" was really arsey and said he'd have to pay him if he broke it. The dad said, incredulously, "what about my son's safety?!"
I said there really needed to be an adult to supervise, that it wasn't safe. He was getting visibly annoyed with me, but I can't believe he though it was fine to let so many kids be unsupervised! It was round the back, where no adults could see them. There seemed to be no time limits (or age restrictions) they just kept piling kids on, and it was getting really crowded. If parents are meant to supervise that should be made clear.
Sorry that was an essay, but had to get it off my chest!
WABU to expect the guy to actually supervise his bouncy castle slide?