Yeah, somehow I don’t think that’s what’s getting drivers hot under the collar.
I’m pretty sure it has more to do with the fact that cyclist’s patterns of movement are much nimbler and more darty than those of larger vehicles and that due to their size, they are considerably harder to see. Couple this with many cyclists’ willingness to move contrary to established traffic rules, and it is not difficult to see why driving in close proximity to cyclists is not a thing that motorists tend to look forward to.