dave kadolph wrote in post #6033215
I respectfully disagree with your blanket statement.
If you are at one of my local school events--AYSO event--AAU basketball--Girls on Track--Girls on the Run--The local hockey rink or indoor soccer facility--Habitat for Humanity--City Rec League--or any of the other places that I have permission and the blessing of the organizers and/or owners I will be friendly and try to accommodate you--but if push comes to shove
I won't be the one leaving.
If I'm taking "the show on the road" to shoot tournaments or away events where I'm not known a polite introduction and inquiry about the local ground rules is always in order.
Jamie is correct--By showing a little common courtesy to parents,coaches, officials, or organizers I've never been denied permission to shoot an event of any kind or gotten into any unpleasant situations.
Getting a prime spot to shoot from--Well that's another story--LOL

My statement presumes the situation stated by the OP -- the photographer is an unknown, with no permission, nor any "reason' for being there.
Certainly, if you are there with the blessing of the organizers, the situation is totally different, and any complaints would be handled with that in mind. The photographer will ultimately prevail in those situations as long as they have conducted themselves professionally.
I, too, have never been denied permission to shoot. I have also been approached by police, building security, and TSA. In all those instances, 5 minutes of my time and a friendly disposition had me back at the viewfinder shooting away. Although, TSA was a little unnerving. 