I just did a 3-day, Protected content road trip with my son across the west coast of Malaysia down to Johor and up to Kedah and Perlis. That has brought the way we Malaysians drive to mind, and maybe some of the causes.
I once heard an expat say that Malaysians don't know how to stick to their lanes. I found that to be very true. We just change lanes without thinking when curves are a bit sharp rather than slowing down so that we stick to our lanes.
I also found some ridiculous speed limits. On the Penang bridge, for example, the speed limit has been brought down to 70 kmph from 80 kmph when I used to stay in Penang. In Cyberjaya where I work, the speed limit on the main road is 50 kmph. The result is that local drivers totally ignore the speed limits and can go to Protected content . They get upset when drivers from out of town (who don't know if there are speed traps) follow the speed limits.