My 3 dc have spent many years doing a full year sport - involving many hours of training multiple days per week. A girl they knew also did the sport, and I volunteered to supervise the child from 330 -630 at the venue so the nanny could leave - I was there any way. The father was supposed to pick up at the venue at the end time. Most nights I'd be standing in the parking lot with 4 hungry kids needing to get home to do homework/dinner/bedtime while trying to get hold of the parents on the cellphone. Father would usually say that he was 20-30min away, and that he would pick up at our house. Couldn't safely leave her at the empty venue. Leading to me feeding an extra child, and disrupted homework and bedtime. This girl liked to play my kids off against one another - not an easy guest.
Any discussion with the mother (a doctor working pt) led to tears about how useless her DH was/how stressed her life was - this said to me, knowing I was on disability and barely coping health wise.
Other times I would drop her off as arranged, but no one would be home. Dropping her off involved an additional 30min transit for me. Cell phone either not answered, or "at the grocery store, be there in 15 or so".
Mom would always start off a new season with "we should share driving/pickup", but would always bail on her turn. I began to dodge any pre-arrangements so she changed her tactics to "last minute emergency" calls, and then to getting her daughter to ask my kids for a ride.
Worst was at a pool party for friends from the sport. The mom asked me part way through what I was doing afterwards - I said driving to a different part of the city (I actually wasn't, but had started to prepare reasons why I couldn't have her child). She flipped, screamed at her child to get out of the pool because I wouldn't take her home later, and bitched to the host that I was a selfish bitch who never helped her out.
Another time we were at a venue about an hour from home. Girl was there with her dad. At the end she asked me for a ride home as her dad had left to go shopping and couldn't make it back. I said I'd drive her to ours and he could pick her up from there - he took an extra 4 hours.
I felt very sorry for the girl as she knew where she was on their priority list. She's incredibly self sufficient as a young adult, having been abandoned by her parents once able to take the bus/get a job. Wonder if she'll be a CF, having learned the CF skills from a young age.
CF attempts only slowed when the kids ended up training with different clubs - still happened at competitions, where we'd end up driving her home.
This sport tends to breed CF parents who are always looking for someone else to do the volunteering, supervising and driving duties for them. I can now spot them a mile away and am prepared with a "nope, won't work for me" as I have no desire or duty to commute hours every week with kids mine don't know/like so their moms can go to exercise class, get their shopping done, etc. I save my efforts and energy for friends, even if no reciprocation is possible.