Well chap, I think we break them for the same reasons you folks driving motor vehicles break them... because you can.
Here's what I see Drivers doing on a daily basis:
Talking on cell phones, rolling stops, speeding, trying to beat yellow lights, failure to signal, driving drunk, driving emotionally unstable, eating, drinking, reading a newspaper, fiddling with your CD player, wearing headphones, racing, cutting off other drivers (and cyclists), clipping the heels of pedestrians, honking your horn incessantly, weaving in the lane, illegal turns, blocking intersections, blocking bike lanes, right hooking cyclists, speeding up at crosswalks, burning cross walks, disregarding school zones, work zones and caution signs, driving with no lights, driving without turn signals or brake lights, driving without brakes(!), driving with a missing headlamp...
I could go on. Look all I ask is that you folks driving 1/2 tons of steel and plastic obey the basic traffic laws designed to keep you in check and from killing the rest fo us who are sharing the roadway. Slow down, get aware and deal with it. Pedestrians, equestrians, cyclists and longhorn sheep are unpredictable. So watch out.
I'm sorry you are stuck in traffic with your brethren, please don't hate others who dare to brave the elements for the sake of fun and avoiding the snarl you're sitting in. Yes I just blew by you in the bike lane and I'm long gone before you get to move 10 more feet. Is that my fault?
It's been a looooong time since the automobile first appeared on our roads and we've all forgotten that motor cars are the VISITORS.
It's why y'all need a license... though the way you gents and lassies drive each day... you couldn't tell you'd had some driver's ed.