When equipment is tested for EMI it is only blasted with one frequency at a time and there are no tests done for multiple frequencies. If you walk around anywhere with a frequency analyser you will find a lot of them! from radio station, to dect phones, mobiles, GPRS data cards, bluetooth and even directional beacons for the helicopters!
I once had a piece of equipment to upgrade the software on and ended up corrupting the thing due to the wireless card inside my laptop!
Mobile phones are just an easy target. but i do agree that some people using phones think that if they shout down the line the person at the other end will understand them better.
