Well, (human) drivers in Singapore are pretty bad (based on a few taxi rides), so there is that. Apparently lane markers are something your are supposed to drive on top of...
The Singapore driving style doesn't make sense if you're used to driving on western roads in western traffic. It makes perfect sense if you think of the lanes as aisles in a packed supermarket, and each car as a trolley. Cars don't so much 'navigate' as 'flock'.
