Robert makes some good points. Funny how the photographer is where they haggle the most and want the cheapest possible price and it is the only thing they will have to remember the wedding. I never understood this attitude.
I remember once I was shooting in the street and a guy stopped by and asked me if I would shoot his wedding. I said, I would love to but I dont have the equipment necessary to do a good job, the guy kept insisting, and I kept giving him the same answer, so finally he said "you wont do it even for a couple of hundred dollars?"...lol....thats when I broke down laughing and told him, you want me to shoot your wedding it would be a couple of thousand!......
He quickly left.....
Doing weddings is one of the hardest jobs there is, so the photographer as Robert points out should be a manager as well as a photographer. He should inspect the venue first hand well in advance of the wedding, plan for the shots and also plan for people who will also take pictures. If the photographer is good and his work is good then he should not be worried about other people shooting, OTOH if he is mediocre then a guest upstaging his photographs might be a worry. The good wedding photographers never even worried about people bringing the cameras, as Robert points out they had planned the photo shoot and talked to the B&G to make sure they understood the schedule, so that all was done as quickly as possible and they could enjoy their wedding.
What they actually told me is that they hated the "video" guy....with his hot light and usually getting in the way of the photographer. Specially since it was the photographer who set up the shot and the video guy would just step in and take advantage. Many of my friends told me that they made sure the B&G knew that the video guy was under his commands, or that they would refuse to shoot the wedding.
So I guess it all depends, if the main photographers shows up with a coolpix and you with a hasselblad, well I can see the problem and how he would not like to have you take pictures. If he OTOH shows up with with professional equipment and looks organized then he should not worry about it, invariable people will want to take pictures and he also should be a diplomat.