In some sense the motorists are right, that cyclists have no right on the road... don't forget almost everyone else has to get training before getting out there. And cyclists don't, and most don't take up the voluntary options (hell, I only have my cycling proficiency circa 1975). So we are the untrained interlopers in a world of trained road users.
I know, I know, I'm just doing the devil's advocate thing... but there is a serious point.
Short answer:
You don't have training to ride your bike because it's not a danger to anyone but you (more or less)
Driver training often counts for bugger all, you learn much more after you pass your test (e.g., main danger is from newly "trained" men aged 18-25 in cars)
Short answer: