In our 9 trips to Disney we have never had someone leave the line to go to the bathroom. I will say that on our last trip my 12 yr old and my 10 yr old went on the Goofy ride and I chose to wait outside the ride, well about 10 mins in, I decided to go wait in the Tinkerbell line, and their cell phones were not working, so I had to go through the line to tell them I was going to start the wait for them, which by the way ended up being SO long, almost 2 hours, but who knew.....the sign said 90, but it was an eternity, but SO worth it...lol but anyways I was horrified at how hard it was to find them in line, and people were not all that gracious about letting me by. But I had to do it, otherwise how would they have found me, and it was about 25 minutes they didnt have to wait in that Tink line. So I can see how some do not like people getting in and out of lines, but I am sure the people do not like having to get out of the line either.