I saw a very similar case to this about 10 years ago. Biker doing an estimated 75-85, reports of him travelling in the centre of the road just prior to the accident, car turning from stationary into a farm on a country road - farm happened to be on a slight bend.
No way the driver could have seen the bike in time to take evasive action, especially on a slight bend, especially from stationary.
Biker was killed. Driver was handed a very similar sentence - massive fine, think it was more than £1,000 - and disqualified from driving for a very long time, which would cause him to lose his job and possibly his house (mortgage issues). He was also suffering from severe mental health problems as a result of the accident.
It struck me at the time how terribly unfair it was, and terrifying, as a driver.
What benefit is to be gained from such harsh punishment? It doesn't even act as a deterrent, I don't think, to other (car drivers).
edamsavestheday I think the brain does scan for car shapes, it also expects a certain part of the obstacle to be in a certain part of the road. If a biker is near to the centre line, it is neither car shaped nor in the area being scanned (I assume you would naturally scan from kerb side rather than centre to kerb). It would also be much harder to gauge the speed of a very different profile, because there is less information for the brain.
I also think humans are gap orientated, so would be looking for gaps. It's entirely feasible that a bike would be read as 'gap' if only part of the image was 'scanned'.