The reality is different, and death penalty actually "ends a life" thing that under no circumstances can be done to any person whatsoever, but doing it as an example in a case of drugs? It's terrible, if I were the judge on that case (or the congresist if any) I don't know if I'll be able to sleep at night...
It boild down to what purpose you think this aspect of the justice system serves. I nthis case, it's as much about detterece as punishment. There's good indications that the crackdwon by Singapore with the death penalty has reducedthe level of trafficking. Personally, if the death penalty reduced the level of pre-meditated murder or serial rape for example, in Ireland, I'd be all for it. Then again I also support the stripping of citizenship and constitutional rights for criminals too, so I'm a tad on the right in these things.
All this also applies to anyone saying he shouldn't die since he hasn't killed, it's a deterrent more than punishment.

People who buy drugs, are not forced to buy them.
The first time. Heroin is an agonist opioid, it creates a physical reduction in endorphin and the short story of this is that this is what creates withdrawal. Most other drugs are antagonist, and as a result less addictive, for example cocaine. heroine creates an actual physical dependency, not a psychological one.
The stuff is pure evil, I'd much rather the US moved their Columbian crop spraying operation to Afghanistan and start cracking down on opium production rather than coke.