The problem here in the UK is that the drivers are all, with a few exeptions driving between 65 and 90 mph. Which means that the real percieved speed is at most 25mph, and in most cases 1 or 2mph in terms of the major reference point, the traffic around you. We tend to ignor the fact that we are travelling @ 70mph
The brain tricks itself into thinking that we are virtually standing still, hense the frustration.
Understand that its a human perception problem and your half way there.
The people not paying attention to the traffic around them, appear to get in the way, but in actual fact are driving without due care and attention, but boredom and tiredness can cause this effect as well.
Calv'