Luckily, I don't have much interaction with motorists on my commute as it's mainly on MUPs. I enjoy the peaceful serenity of a cobbled path in the woods on my commute. Stress free. I certainly don't envy you folks that commute in metro areas.
Every once in a while I have "problems" with pedestrians on the trails. Sometimes they'll be walking against traffic - on the left side of the trail instead of the right and they won't budge forcing me to go around them. If they're three or even four abreast across the trail, I give them a quick "ding,ding,ding" on my Incredibell and then they move over.