Les.
Yes, of course, bad driving causes accidents, but the 'innocent' driver involved could have avoided the accident in many cases if he/she were driving more carefully.
Experienced Motorcyclists and experienced cyclists drive defensively (as of course they always come off worst no matter who is to blame) and thus they try not to put themselves into positions where the actions of bad drivers might kill them. Many car drivers don't think that way, thus may not make sufficient allowances for 'dodgy' drivers. So when they are involved in accidents, in which they were not overtly to blame, they are less likely to realise that they were a contributory factor and that more care on their part may have prevented the accident.
But, as I said, we all know we are great drivers, so I don't expect many to agree.