Why wouldn't I still talk to the other kids parents when they are 15? I still need to know what they are doing and who they are hanging out with and who's driving them around.
If my 15 year old tells me she is spending the night at someone's house, I'm certainly going to call and talk to that parent and make sure that's what's going on. I remember being 15 and the cr*p I tried to get away with
Spending the night at someone's house is different, IMO, than going to a party & then needing a ride home.
I remember my DD went to a bonfire at a friends house when she was 15. When I took her I went to the door just to make sure a parent was home. She was mortified, of course, but oh well. I would have been more concerned that there was supervision at this party than "find a ride home".
At the very least this parent should have said, please try to get another parent to pick you up, if you can't call me as a last resort. Not just leave them there.
That's essentially what the parent said. In fact, who knows, maybe the mom said, "I can't pick you up, you can get a ride home, right?" and the girls might have told her it wasn't a problem & the OP's DD called her for the ride.
Here's how the conversations usually went in our house:
DD: Mom, we're going to the football game tonight. Can you take use there & can we pick up Ali & Katie on the way home?
Me: Sure, how are you getting home?
DD: Either Ali or Katie's mom, but we'll let you know for sure because Katie's mom & dad are going out so they're not sure & I think Ali's parents will be at the game but I don't know what they're doing after.
Me: OK, well, dad & I are going to dinner so text me & let me know the definite plans when you find out. If we have to we can come pick you up, but it would be easier if another parent could do it.
DD: OK, I'll text you as soon as we know.
No biggie. The plans weren't definite. I didn't have to talk to any parents (although I pretty much know/knew/have at least met most of the parents). Really, as your kids get older you have to trust that they can make these arrangements themselves.
I would be annoyed if the parents really did a drop & run without thought of how the girls would get home, but I would just know better for next time. I wouldn't get in a tizzy about it.