I am and have been a photojournalist for 40 yrs now. I have some insight on this subject! TV WANTS us to be there with the sounds and sights of still photogs moving and clicking away. It legitimizes their existance at an event! The politicians would DIE if we WEREN'T there, we ALSO legitimize their being there as well!
We are there to capture THE moment as stated in a reply above. Im a Canon X body shooter, nothing is silent about that camera! The X2 has a good silent mode BUT to get silent you give up speed and you cant give up speed...! Editors want expression, reaction and quality. Its like the Lays potato chip ad.. you cant eat or shoot just one! Your next photo MIGHT be "THE PHOTO" so we shoot in hopes that the next one is the best one, plain and simple! They are called press conferences for a reason not public relations conferences. With the presence of one photog and reporter thousands upon thousands of people are informed of what occurred at the presser (if the reporter doesnt slant the coverage) I or we only worry about the "noise" at certain events and a presser isnt one of em!

I photography a LOT of events with political speakers and frequently put my camera in high-speed drive in order to get the best image possible. Many people have highly mobile faces when speaking and that frequently makes the number of 'less than flattering' images to acceptable images 10 to 1 or worse. Silent mode slows the camera down too much and it isn't possible to accurately time when a speaker's face is going to be in what we 'see' as a normal position. It's unacceptable to finish an event without great images of each speaker. The good news is that in high-speed mode, the D5 is quieter than the D3 and the D500 is much quieter than even the D5. In the film days I still used a motor drive on my F2, it just didn't rock along at 10 frames a second. Technology is improving!

Just watching a trump media event with our prime minister Justin Trudeau, and you can barely hear them talk because there is an extremely noisy background barrage of camera shutters. How annoying! Two questions:

1. Why on earth do the photographers need 100's if not 1000's of photos to get one good enough for their media platform?

2. Why on earth do they NOT put there cameras in " silent mode"? My 5D has this feature and I assume most cameras do as well. Professional photographers have high end cameras that must offer a silent mode. I don't believe they are using flash since the lighting is very good so we can't blame it on flashes.

Louis