Playground Rant...

I just wanted to rant a little bit about what happened today at the playground. I'm a nanny to 2 year old twins, and during the summer we are on the playground every day. Today, one of my charges was playing with another kiddo, that I'm guessing is similar age as he moved very alike (the unmistakable 2 year old half-running-half-waddling), and was similar size to my charge. My charge was yelling "I catch you!" at the other kid, they laughed, they would stop and giggle, and then the other would start the chasing. This went for a while, while the other kiddo's mother was clearly busy on her phone, and not paying attention. Since my other charge was happy to stand beside me and laugh at their antics, I had no problem watching all 3 kids. As with all toddlers, the laughing and running ended with a fall. My charge run into the other kiddo, and they both tumbled. I got in there to make sure everything is fine, and they were both still laughing. My charge had a skinned knee, while the other kid, scratched nose. As I was helping both of them back to their feet, my charge started yelling again 'I catch you' clearly wanting to restart the game. At this time, the mother seems to have looked up from her phone, and started running towards us and screaming 'what happened, what happened'. As soon as she saw her kiddo, she started yelling 'Oh God, Oh God he's hurt, he's too young to understand!' clearly very upset. All her screaming upset both my charge, and her kid. Her kid started to cry, and my charge started to say "Luke did hurt.." clearly getting very upset, and nearly plastered to my knee. My other charge was also getting scared, and starting to cry. I started to say to the mother that they were just playing and having fun, but the mother was getting more and more freaked out. I started to console both my charges that everything is fine, and that they didn't do anything wrong, which seemed to have enraged the mother even more. Finally I snapped at her that perhaps she should be paying attention to her kid if she doesn't want him running, while taking both kids away from her. She fumed for a bit and then left the playground.
I absolutely hate those kind of parents/guardians on the playground, a weird hybrid of overprotective with too busy to pay attention. While I don't like my charges getting hurt, I let them run, climb, play with other kids, and such, because I want them to grow up independent and confident. If they fall, I get them up, and after a quick hug or a kiss to owie, I set them to play again. If there's blood, we simply go to clean it up and then with 'let's be more careful, ok?', I set them off. My charges know to stay away from swings, share toys, play hide and seek, it, play ball with others, climb ladders and tall slides, push marry-go-round, etc. When another child plays to roughly with any of my charges or the other way around, I correct them with a smile by saying things like 'how about we do it a little slower' or 'let's let the big/other kids play on this', 'let's be very gentle with the baby' or 'it's for big girls/boys'.
Has anyone had a bad experience on a playground too? What is your worst pet peeve when it comes to playgrounds?