It really is frightning how many incompetent drivers are willing to happily admit that their inability to carry out basic driving manoevures such as joining a motorway off a slip road, overtaking on a motorway and changing lanes adversely affects their driving.
As well as a basic skill in driving, the above are also pretty damned logical - if you cannot do this correctly, why on earth not find out how to drive safely??
I had one typical but potentially dangerous incident on the M90 (two lanes motorway) last weekend - road ahead was empty, broad daylight, except one car sitting in the outside (only overtaking) lane about two miles ahead. It was doing less than 70mph, because I caught it up. Perhaps it was doing about 60mph. I sat politely behind for a mile or so, hoping the driver would notice me and move in. Nope. I put on my right indicator, which is a signal someone wants past. Nothing. Another car came up behind me and began to tailgate me for sitting in the overtaking lane without overtaking but then realised what was happening and backed off. Now the first driver noticed, stared at me in his rearview mirror for a bit, then moved over deliberately slowly, straddling both lanes for 30s or so. I had thought I was going to be able to overtake normally and had to abort my manoevure by slowing because of this, and the car behind me nearly ran into the back of me.
As I overtook the first car, the guy gave me a sort of sarcastic wave. I ignored him (I try to avoid and not react to dangerous drivers) but the car driver behind me drove alongside him for a while with his lights flashing and beeping and gesticulating - it looked as though it was going to be a road rage attack.
Fortunately there was no accident, but I have no doubt that the incompetent first driver thinks himself a great, safe driver, and I'd rather meet the second driver on the road anyway, who although faster, was far more aware.