Yellowstone and other national parks have a big problem with wildlife and tourists who apparently think that they are in Disneyland. "These animals -- they're tame, aren't they? Like, they wouldn't let
wild animals out around people, right?"
There are big warnings in the handouts now -- "DO NOT ATTEMPT TO TAKE SELFIES WITH ANY ANIMAL."
That being said, the last time we were in Yellowstone at least some people had gotten the message. There was a bull elk lying in a stand of trees about 50 feet from the Old Faithful-area toilets, and people were being very, very quiet, holding children by the hand and taking pictures from a safe distance.