I've read all the replies to date and it strikes me that we all have the same dislikes when it comes to other peoples driving standards.
For my two penn'orth, people at roundabouts in the left hand lane who want to turn right and vice versa, the hat normally gives them away....
Coach drivers who, unlike truckers, never acknowledge you when you let them out.
Truckers who have to prove to everyone that they can do 0.025 MPH faster than the 10 that they want to overtake with a stream of irate people behind them.
The list is endless, experience will highlight these sort of people, the trick is learning how to avoid them (or wind them up...).
Lack of driver training has been pointed out in these forums, its not the case, we're all taught the same basics, but when we get that little piece of pink paper telling us we can venture out on the queens highway, selfishness comes to the fore.
The fact is, we live in a society where everything one owns or does has to be bigger/better/brighter/more than the next person
. "I want it now" seems to be the order of the day and nothing will stop someone from achieving their goal, whether socially or on the highway.