The reason it concerns me when I see something like that
isn't that it annoys me or I resent someone else breaking the rules just because I like rules.
It's stressful for me to witness other people in danger.
On my last trip, we saw a man collapse and be carried away by paramedics at the hotel; his face was covered, so I assume he was dead. Of course it was worse for his family than it was for me, but it was still awful. I've also seen people fall or nearly fall off
ECV's, and it would be a horrible thing to witness someone getting severely injured as a result.
On the same trip, I rode the train around the Magic Kingdom behind a family who ignored the instructions to put small children between two adults instead of at the end of the row, and put a little girl of no more than four on the far end. They proceeded to completely ignore her as she hung her arms and legs out of the train, reaching for tree branches as we went by. I didn't dare say anything to the adults, becuase they were yelling and screaming at each other, obviously in a terrible mood, and would probably have turned their anger on me if I'd interrupted them. However, I rode the entire way poised to spring up and grab the kid at the first sign of danger. I was even prepared to stay on the train if they didn't get off at my intended stop. My heart was in my throat, because I knew I was the only thing standing between that child and death or dismemberment. Sure, it was technically not my responsibility to worry, but what kind of human being would I be if I didn't care? I don't want some poor, innocent little kid dying in front of me because I wanted to just "get over it and not worry about other people's vacations." My mother watched a classmate die on the playground after a fall when she was little, and later had one of her own children die at a babysitter's while she was at work. Both incidents have haunted her all her life, and it's not because she's some busybody who wants to harsh other peoples' buzzes.
There's also the fact that an ECV accident could injure not just the driver/rider, but innocent bystanders, too - innocent bystanders like myself, who sometimes can't get out of the way very quickly.
So, no, there's not much you can do when you witness unsafe operation,
but I hate to see people scolding the OP for even caring.