I certainly don't equate marijuana to beating people (where did that word marijuana came from? It was about drugs. What about Krok? [1] Besides, you could count the victims of the drug scene, the mafia, gangs and everything that is behind drugs, bribe, weapons or prostitution. Buying drugs sponsors crime).
Anyway, back to topic.
The point is that Singapore has one of the lowest crime rates in the world [2], that doesn't come ouf of nowhere and is bought with very strict laws.
Actually i was trying to make a point to not equate your own understanding of legality with another. We are all bound by certain laws and what we take for granted may sound very strange to others. For example, i find it very, very strange that, in the U.S., people are allowed to carry guns. Can't get it in my head. But well...
[1] http://io9.com/5859291/krokodil-russias-designer-drug-that-w...
[2] https://en.wikipedia.org/wiki/Crime_in_Singapore