Complicated by the fact that you all drive on the wrong side of the road, I can't visualize what this driving is that you're describing. We have enough fools to go around over here in the U.S., though, that I can take a guess. Different states here post more or less about how one should treat the far left lane. Traditionally it is for passing. The right lane is for normal travel and the slow-pokes should stay there. They often don't. They tool down the middle (perhaps the same problem you're describing) forcing one to pass on the left (where you're supposed to do it) or pass on the right
(we have a bumper sticker <- passing side | suicide -> )

Good luck!

SRS