As much as I love my kids (now grown and left home,) this is one thing I do NOT miss about having young/school age kids. The dreaded 'hobby groups.'
Some may say it's part of what you sign up for when having kids, but as much as I enjoyed going swimming with them, playing table-tennis and badminton, and taking them to the park, and to the zoo, and to the beach, and going on little shopping trips with them, etc etc etc, I did NOT enjoy their 'hobby groups' and 'extra curricular activities.'
They had karate, footie, drama and dance club, singing lessons, golf lessons, netball, and several other hobby groups, and I either had to take them and hang around while they were there, (anything from one and a half to three hours,) OR I had to drop them off and pick them up later, and could not do anything else with the day as I was waiting around for them. Sometimes DH was with me, or he did it, but as he worked more hours than me/had a long commute, it was me 70% of the time.
@Emergencyblueberries
You have my sympathy OP, and I am sorry, but it's not going to get any better. This is only the beginning. When I was a kid, I made my own entertainment and went out to play with friends, and yeah, my folks were good parents and took me to the beach a couple of times a year, showed me a great Christmas, (and birthday,) and we went to the zoo and park now and again. But there was none of this bullshit of parents being expected to put everything in their life on hold, and cow-tow to every little hobby and interest their child had, and be there all the time to 'help out' in the group, and escort them everywhere. What utter bollocks.
And these days, parents are busier, more stressed, and work longer hours, and more mums work too!)
Don;t know what to suggest without upsetting your daughter, but YANBU.
Also, I swear it's a money making exercise sometimes; charging for the kids to run round in circles with a fairy wand for an hour, then £16 each for the tickets?! It's like this 'your child has had a short story published in an anthology of short stories' crap from school, with an 'offer' for you to buy 3 of the anthologies for the price of 2. Only £40 for the 2 instead of £60! Then you discover every kid in the class has a short story in it.
Parents are made mugs of these days, I swear.... 
And yeah it may be 'perfectly normal' for some dance schools, but that doesn't mean parents (mothers!) have to accept it. Some mothers do actually have busy lives, and an actual job, and don't have the time or patience for these kinds of demands!
I also find it beyond bizarre that the dance school is demanding the children miss school for the show! WTAF?
Who do they think they are? Seriously..........?