Why can't cyclists and drivers all just get along?

From the SeattlePI.Com:

About 8:40 a.m. Feb. 5, a bicyclist told police he was at the south side of the crosswalk at Sixth Avenue and James Street - the southwest corner - and saw a silver Honda CR-V that he didn't think was going to yield to him on his bike at the marked crosswalk.

The CR-V driver came to a quick stop, and "as he crossed he said, 'Are you going to stop?'" according to a police report. The driver of the CR-V and the cyclist swore back and forth at each other, police

A witness observed the two men yelling and swearing at each other. He observed the bicyclist throw his bike down and "puff up his chest as he said, 'Come on,'" according to the report. The suspect then got out of his vehicle instead of driving off, and they started yelling until a fight ensued, the witness said.