Kids can be quite stressful when you are around horses. I've delt with a lot though, guiding public trail rides when I was younger, so you had a lot of people who didn't know squat about horses with little unruly kids running about. Before a kid even comes around my horses, (even though my horses are all level headed and kind) I give them the speech about being behind a horse, going under one, making loud unexpected moves, getting bit, petting them without supervision ect... 8 out of 10 times we don't have problems. However you do run into those kids that do things that make you cringe and thank god your horse is sane. Say a kid runs right behind a horse without a thought -I let them know that wasn't a smart move and tell them what they need to do in an authoritative yet kind manner. HOWEVER when they commit the same offense over and over -that I have specifically gone over and told them more than once NOT TO DO that's when I start getting upset and let them know that if they do it one more time, for their safety, I am going to have to ask them to stay completely clear of the horses until I say otherwise.
As far as kids spooking my horses, that's happened plenty times walking through a campground. I now turn on high alert if I'm riding around general public areas now too!
Things that have REALLY made me mad? People on dirt bikes. Now usually you hear them coming, get off the trail and face your horse towards them. Usually, when they see you they slow way down or I've had people who'll kill it instantly and just slide to a stop. Love them!
However, one time in particular I was about 10 yrs old riding around the trails by my house and 2 dirt bikes came up on me. When the riders saw me the one leading sped up and slung gravel at me as they passed and the second rider reared up on a wheely and reved really loudly no more than 10 ft from me.
That's what makes me mad. I've also been chased before in a truck by un-known persons. Talk about scary. O.o
So really most acts that spooks my horse, committed innocently, doesn't get me too riled up.