Sorry.. I have to tell you. You are the kind of photographers I truly hate. Many many times while I am an official photographer, and I have to jostle with people like you, I get really really pissed. You are invading my working space.
And honestly, I am not very kind to people like you. I have clobbered a couple of people like you on the top of their heads with my lenses before, try knocking your head onto a 300 f/2.8 or 200-400.. its painful.
If you were jostling with press photographers, I can tell you.. expect a bruise or two, or more, or even be shoved till you end up falling down.
We make a living, and each shot is $$ for us, especially if you are talking about things like graduations, prize giving and/or weddings. Its a one time shot. We cannot ask them to represent the cert.
In such situations I also take case with the organizers. They should have better crowd control.
Even if I am a volunteer official photographer, I still have the space. I ahve shot many charity events as a volunteer official photographer. Once the organizers have appointed you as official, you have the pressure to deliver.