Drivers who are impatient toward cyclists are mostly taking out the frustrations caused by other cars on a visibly weaker and vulnerable road user. You wonder what would happen if a cyclist stopped in the middle of the lane? Car drivers do this all the time and they call it "double parking". Parked and double-parked cars use the majority of the road space and then drivers act like it's the cyclists who are delaying them. Fact is no cyclist has ever considered stopping needlessly in the middle of a lane. They do have places to go and a reasonable expectation of the enjoyment of the right-of-way in safety and comfort, however. Cyclists should and will operate at least 4 feet away from any parked cars, to avoid the "door zone". Drivers should anticipate this lane position from all cyclists, and should respond by staying a respectful distance behind the cyclist, chilling the fuck out, and passing if and only if a safe and legal opportunity presents itself. Any other expectation is just drivers being entitled pricks.