Having recently started to commute to work on the bike (only one way at the moment til I can get used to doing 18 miles each way), I can say first had that there are a lot of numpties out there on bikes and fully support some kind of bike test, even if its just theory. The amount of idiotic moves I have seen just in the past 2 weeks of commuting is unbelievable it really is. And thats not even inner city riding.
On the flip side, I can now also see where bikers come from that have a go at a vast amount of car/van drivers. Just yesterday I was coming down a country lane where I knew it was not safe to overtake, so I took up the road somewhere between primary and secondar position, and yet a f'in white van man decided he wanted a go anyway. Well as you can guess, what comes around the bend but a car coming in the other direction and they nearly had a head on collision had I not backed off and let the van back in - not that I had any say on the matter! While cyclists need to learn to ride the roads properly, drivers also need proper training that if someone is taking the primary position, this means you should only overtake if you can do so safely as if you were overtaking a car, not try to squeeze through. I will now make sure I always hold the primary position properly in these cases so the feckers can't possibly try and squeeze past