In my case the "wrong" side of the road has a 10-15 foot wide shoulder to ride in, while the "right" side of the road has no shoulder due to a double intersection of two 5-lane streets and a 2-lane street. Riding the left shoulder where there are no cars is preferable to crossing a right-turn lane and two lanes of 50MPH traffic through a large double intersection to get to the left turn lane for my left turn at the second half of the intersection. After that left turn I'd need to get onto the protected left shoulder/sidewalk of the next road anyway since there is no right shoulder on that narrow rolling road and extremely poor sightlines with very fast downhill traffic that makes it totally unsafe on a bike IMO.
So, if I ride the left shoulder to my left turn onto the protected left shoulder of the next road I don't have to encounter any automobiles at all, and if I encounter a bike or ped there's plenty of room to pass. If I ride "as traffic" on the right side of the road I have to cross several lanes of fast traffic trying to rocket through the light and end up in a lane on the next road that I refuse to ride a bike on anyway.