The first reason cabs in Bangkok are dangerous is that cab-drivers in Bangkok have no fear, and after you've been in a cab doing 120 kmh approximately three inches from the tires of a semi doing 80, well, then you appreciate a nervous driver.

The second reason is that cab-drivers take amphetamines to stay awake. This allows them to make more money, but unfortunately, it also drives them slowly insane. Every so often one of them snaps. The results are not pretty. Machetes, guns, that kind of thing.