I do a summer choir trip that normally overlaps the end of term and goes into the summer holiday. The kids are 14-18 and the vast majority are lovely. However, it is bloody hard work.
The last foreign one was to S Germany. One parent of a y9 lad said he couldn't be trusted so I had to look after his passport and EHIC. We did a lot of border crossings between Germany & Switzerland & Austria so I had to take it out each day. We have to make sure everyone knows which uniform we are taking out for the day. One kid never had black shoes - always used to wander around barefoot so someone had to take her out to buy some. Then there are the food allergies and making sure they get fed first so others don't take all their food. On the last trip we were split across 2 flights. Mine was delayed so when we arrived, the only food available was McDonalds. Most kids were really happy to wolf that down, but of course there were a couple of little darlings who had never had a Maccy Ds before...
On my 1st ever trip as an NQT to Scotland, we had a disco on the last night. One kid spent all his pocket money on bottles of cola and skittles then ended up fitting at night. The Head of Year went to hospital with him (ringing his mum first who went ballistic at US for allowing him to eat/drink crap) and the rest of us had to clear the place, pack the coach & sort everything out. It wasn't fun.
We organise our choir trips ourselves. Adults don't have to pay, but we do put a shift in. Like @Daffodilz, I have stayed in the Youth Hostel in Nuremberg. The rooms are TINY and the curtains only cover half the window. When we were there, some non-choir kids were inter-railing and thought they would meet up with us. Some of the worst girls decided to try sneaking out to meet them to go clubbing - one of the miscreants was a governor's child. They forgot that we were also teens once. However, for the 3 people that ended up sorting it out, the next day is a killer on hardly any sleep.
On the flip side, I have been to some amazing places. My older daughter spent her 18th birthday in Venice and got to sing in St Mark's with us, which was just amazing. Most parents thank us, but there are a few who moan that we are earlier/later than the original letter said. Heathrow in July is not ideal. We then have to find our coaches and travel at least 3 hours to get back here. With the best will in the world it's not easy.
OP cut teachers some slack. It's been a really tough 2 years. If you're that bothered, take your own kid skiing and stop moaning about adults who give up their free time to ensure yours gets a treat.