At Trailer Village at the Grand Canyon last September, the Elk were in rut and the males were very aggressive and all over the campground. My wife and another woman were taking pictures from a distance when a man walked by them and right to a very large male elk. That Elk immediately charged the man, who moved very quickly. We were talking to a Ranger about it and she said that a few days prior, some parents put their kids on the back of an Elk to "ride it".
In Yellowstone one year, we pulled over to watch a Grizzly bear walking along a creek. Everybody stayed their distance and a park ranger was watching and tracking the bear. A minivan pulled up and the parents opened the sliding door to let their kids out to chase after the bear; which they did, running across the filed towards the bear. The ranger pulled her rifle out and was aiming at the bear while yelling for the kids to get back. Thankfully they did stop, and the ranger was furious with the parents. I doubt very much if they understood though.
It is amazing what you see traveling this country.