[tedsanders]

There are three reasons to drive slowly in the right lane.

(1) It's safer (matching speeds reduces odds of and damage from collisions)

(2) It's more efficient (If you zoom ahead, there is a nonzero chance that drivers in the left lane will be annoyed and attempt to block you, reducing global efficiency. Note that there's no loss in going slow since the bottleneck is the constraint. As a result, going slow can only gain and never cost.)

(3) It's fairest (people who arrive at the same time will leave at the same time, regardless of their lane)

Another comment lays out my logic further: https://news.ycombinator.com/item?id=8084137

I know it feels silly to drive slowly in the right lane, but it's safer, more efficient, and fairest. Why wouldn't you do it?