Agreed. I used to think that way, as it seemed logical.
However, Cell phones, sneakers, iPods, etc are all legal and freely available, but people (especially in UK) get shot or stabbed to death on the streets regularly by somebody that doesn't want to pay for one.
Low level violence of the sort you describe in places like the UK occurs because citizens don’t have the right nor the means to defend themselves from it, and because the legal system is completely overboard in protecting the accused.
Violence like this War on Drugs incident, which is pretty obviously a planned hit on the police commander, happen because there is an artificial scarcity created by the government making drugs illegal. Economics 101 says that artificial scarcity drives up prices. There’s so much money involved, that people are willing to ignore the illegality and to kill over it.
Two very different situations.
The War on Drugs really *is* a quagmire. We haven’t managed to change human nature in the 50 or so years we’ve been fighting it. What makes you think doing more of the same will net a different result?
The Lord of the Flies.