There's little doubt that a hate / hate relationship exists between many drivers and cyclists. It's certainly true cyclists have a right to use the road but I suspect one problem a lot of car drivers have is that cyclists appear to believe the highway code only applies to everyone else.
I've seen them happily ignore red lights, ride on pavements, abruptly turn right without any signals and many seem to believe it's perfectly okay for them to ride the wrong way on one-way streets. Of course, it's only fair to point out that I've seen the same performances from drivers...
Another issue is that they universally appear to lay blame for any problems at the feet (or wheels) of the driver. Why, for instance, is there no requirement for cyclists to be insured, why are there no requirements for them to wear fluorescent colours when cycling along roads and why do so many seem to assume that the rules are only made for drivers?
The usual argument advanced by the cycling fraternity is that cars are lethal weapons, whereas cycles can't hurt anyone, although someone in London was killed by a cyclist going through a red light. But cycles are now becoming frequent road users, and whereas many do cycle extremely well there's a growing minority that seem to actively resent any move towards making them accountable for their road behaviour.