Half of the time it's chancers, the other half of the time it's just fuckwits with no common sense, I once managed to splatter a vauxhall corsa across the front of a military landrover in Reading town centre, he thought he could get across before I went past, he was wrong. Sadly on a bike it just isn't that simple.
Definitely flag it up to the police, they may already be known for drink driving etc, and at the least it gives you some sort of official record of it happening.