Regarding having to pay for it. In the UK, a g of what, 20% pure heroin currently costs somewhere in the region of £50. You might extrapolate from that that a g of pure would be worth £250.
A g of pure pharma diamorphine costs somewhere in the region of £3.
Sensible pricing would therefore see the price drop dramatically and no grannies would be getting mugged.
Er, I don't have to point out the problem with selling heroin for £3 a gram over the counter. Rather the government tax the shite out of it and I get my granny beat up, personally.
Regarding gangs.
Staggeringly askew understanding of the situation and not very christian of you either. The Mexico drug war is estimated to be responsible for 70000+ deaths so far. Many of these deaths, maybe even the majority of these deaths, are innocent bystanders getting decapitated for living in the wrong place at the wrong time.
There are swathes of central America that are currently lawless. Large parts of Mexico and Honduras are ruled by gangs openly running around in big SUVs toting assault rifles. The police have run away. Or joined the gangs. If you live in these areas, your life is in the hands of criminals. This is why a multitude of ex-leaders in central and south America are calling for an end to the war on drugs via legalization.
http://www.bbc.co.uk/news/world-us-canada-13624303
http://www.theguardian.com/world/2012/apr/07/war-drugs-latin-american-leaders
If I go and hike up Snowdon, there is a tourist path which most use. Now, being the cool action man I am... I may go for a very exposed scramble without a rope or anything... If I fall off, it's my own fault for choosing that path. I knew the risks, I knew I could have taken another path... yet I proceeded.
If the government banned all people from going up Snowdon because of my death, it wouldn't be fair on them. Why should those who choose to walk up safely be prohibited from doing so just because I chose a stupid path against advice?
Likewise, if someone chooses a path in life of crime and warfare and they end up getting shot or knived... Why must I have heroin £3 a gram over the counter in my country? Why must I be smoking it right now coz it's just too tempting to take at that price and see my friends and vulnerable people getting addicted also? Just to protect those who chose who would have deliberately chosen a dangerous way of life?
The Bible doesn't disagree with me also, people are allowed to make bad choices...broad is the path of destruction and all that.
And as for your quotation of Lawlwess parts of Mexico ruled by gangs and no police... well that's not really applicable to our country at all is it? I can't see us on the brink of anarchy any time soon. I accept the transfer of drugs across the world and possibly to our country helps fund these criminals, but I don't think the problem is big enough to warrant a worldwide legalisation of drugs quite yet.