A nation of tailgaters

What is it with people these days tailgating like mad? Is my cars speedo that out of wack that I'm slower than everyone else? I'm doing 50mph on a 50mph road, hell I'm doing just above that speed as show on my speedo just in case its out and I'm still being tailed by some mad cunt (normally in a vaxuhall). I can understand the frustration being behind someone doing 40 in a 60 but I'm keeping up with traffic, and whats more galling is that when they have the chance to overtake, THEY DON'T! They just sit there, glued to my arse....

Or better yet, when we're all stuck in a line of traffic behind someone doing 40 in a 60, what difference does it make tailgating me when the slow car is 9 fucking cars in front!