Not that I'm on the side of anyone who drives and knocks off a cyclist, but as one who does drive all sorts of vehicles from a bicycle up to (at present) a 25 ton truck - the latter not in the UK - I have some sympathy with the car driver. The human brain is a wonderful thing - it processes visual information without us realizing it, and one of its tricks is to disregard information it thinks is insignificant.
What has that to do with anything? Probably a whole lot in the classic 'sorry mate I didn't see you'' scenario. It's entirely possible for a motor vehicle driver to look fully at a cyclist (or a motorbike rider) and not see him or her at all - because unconsciously the brain is tuned to vehicles of a minimum size, and especially when viewed from the front a cyclist can be dismissed by the motorist's brain until suddenly 'you came out of nowhere' and a collision or near miss results.
I've never hit a cyclist or a motorcyclist because I didn't see him - but I've almost done it on more than one occasion, because I didn't register that they were there even though I'd seen them.
If there's a point to this, when we're on two wheels we should not be surprised when it happens, because it probably WILL happen. We all get older, and as motorists it's likely that we may become more prone to this sort of thing. All those 'think bike' campaigns are intended to make the motorist realize that there are relatively small vehicles on the road and they must guard against the brain's ability to look at and then dismiss them. Of course it doesn't always work, and a motorist might never realize that the danger exists until too late, and even then not understand what might have happened in order to learn from it.
Of course you've also got to be lucky - as a motorist or as a cyclist! Some say that the avoidance of accidents is not a matter of luck, but I think it must feature to some extent. We all have to give it a helping hand by being aware of what can happen, and why.
Rog.