Unacceptable

It's not about the mistake, it's about what you do or say to make amends/apologise. We can all mistakes, but if I had done that to my mum (or anyone, in fact) it would never ever happen again, and I would have been hugely apologetic, bought flowers, and I would've been the one to suggest a method for that situation to never occur again, whereby I would lead the messaging etc, not expect her to. I'd be terrified if I was collecting someone else's child who appeared to have gone missing, and I would feel so incredibly bad if I'd ever put someone else in that situation. However, sometimes mistakes happen, and unless her attitude is a little too casual about it all, move on. Otherwise, maybe a time to step back a bit, and not be taken for granted.

Your daughter made a mistake and apologised when she realised her oversight. It was highly irritating and time wasting for you but these things happen. Just have a chunter to yourself and let it go.

Once is a mistake and can be accepted, if it happened again the sky would come down on my Daughters shoulders.

How annoying for you but, if it's a one-off, forget it. I imagine most of us have forgotten something.

I think it's pretty inexcusable. She should send you some flowers for your inconvenience.

Message withdrawn at poster's request.

The trouble, people get away too often with” I didn’t think” or “I forgot’. It’s annoying that they didn’t “think” to tell you they were going away even!
I’m a bit intolerant of people who “forget”. It’s more a case of “I didn’t think to remember” usually.
If you could remember to go to the school they should have remembered to tell you not to!!
It’s not worth falling out about though!

I would be really angry, and also very disappointed with my DD. She obviously is happy to use you as a taxi service but doesn't think enough about you to tell you that they were going away. And I don't mean just letting you know that your services would not be required, but just generally letting you know what they were up to. It's not as if you live a few minutes from the school. Inside I would be seething and hurt. But would I say anything? Probably not, but that is because I hate confrontation, not because nothing needs to be said. Try and tell her that next time you are not needed she must let you know and that you were deeply anxious and worried about why your GS had not appeared, as well as feeling slightly foolish!

I would be disappointed and sad and SEETHING.hope they make it up to you.

I would have been very upset, but I would not fall out with my children over it. I know they would be mortified to have needlessly put me to that much bother.

You are not being unreasonable - it would have been very stressful waiting there wondering what had happened, had there been an accident or had someone else picked him up unlawfully? That's if you tend to catastrophize like I do ;-)
My question is - Why didn't your daughter advise you that they were going away? If she had done, then you would have immediately said "so you don't need me to do school pick-up on the Monday then?". What if there was an emergency while they were away or you needed to contact them but assumed they should be home but weren't? (there I go again....)