Where was someone to give the cop a ticket for tailgating?
Also he failed to use his turn signals while changing lanes.
That's beyond tailgating, that's a straight 'get the fuck out of the way' signal. There are certain drivers who can't take a hint. I've seen people drive 50mph in the fast lane and ignore tailgating, light flashes, and horn honks. Ironically it's these drivers that cause more accidents than actual tailgaters. Since these idiots are taking up the pass lane, other cars are forced to make unsafe passes when behind these cars.
Like it or not, tailgaters are better than stubborn fast lane crowder. It actually takes a certain level of confidence and skill to be able to tailgate closely. Not to mention that it forces you to pay very close attention to slight changes in the vehicle in front of you.