Really? I almost never see cars actually stop and a stop sign. Stop means you rest. Maybe in the US it is different, but in Europe most people will still be rolling ever so slightly. That, too, in theory is breaking the law.

And how about motorcycles? It is against the law for them to ride between lanes, yet I never see them being called out for it when they do it to avoid traffic.

Rules are meant to keep society in check, does not mean that they are absolute. Matter of fact is, the passenger in the car is just pissed off that they cannot do the same - simply run a stop sign. That and probably a general dislike for cyclists because they feel infringed upon (a la "how dare they make me slow down and wait to overtake them, they shouldn't be on the road").