I've maybe gone a bit OT. My point is, whether drivers are competent or not, many of them drive like idiots to varying degrees. Surely many of us on here drive in built up areas on a regular basis. You're trying to tell me cars aren't darting around here there everywhere at excessive speed, not leaving sufficient gaps etc? Just try watching some of the compilation videos on YT, many of those that post videos thinking someone else is in the wrong seem oblivious to the fact they themselves are often a contributing factor to the incident.
I would judge 90% of drivers had considerable room to improve their driving quite dramatically, some of what I see is absolutely appalling. The big surprise is that for the most part they get away with it and there are not more accidents due to poor driving and impatience.