A few thoughts...
It's obvious the tagging could never work, but while people in positions of power remain technically ignorant they'll continue to think it will.
Although all sorts of people commit all sorts of crimes, it could be argued that the majority of crimes that are commonly committed and considered relatively serious (theft/assault etc.) are committed by those who are either a) addicted to drugs of some sort or b) from a social group that doesn't consider the criminal behaviour to be a bad thing.
The former is a difficult thing to sort. Legalising drugs doesn't really help. One possible solution would be compulsory treatment for addicts & ensuring that prisons are drug free to prevent the problem repeating. (Latter should be doable in a closed environment!). Free drugs might prevent the criminality but all you'd do is end up with a social problem & cost instead.
The latter is surely fixable. Most people choose not to commit crimes because of social pressure, and because they have things they don't want to lose like jobs and houses. Remove the social pressure, and having nothing much to lose surely makes you more likely to give into temptation? How to fix this is difficult, I would guess the only real possibility is to introduce consequences of some sort e.g. given direct aid instead of cash benefits, communal accommodation, maybe even group punishment ('cos if other get consequences, they stop you doing bad things in the first place!).
Not that the above is workable, but the current situation doesn't exactly work, and being nice & giving a slap on the wrist doesn't look like it'd work either.
Ultimately only consequences alter behaviour. In the absence of consequences, people will do whatever they feel like.
Re: the Ecstasy comment earlier; having taken a drug isn't an issue, and you won't get arrested for it - only for possession. So it seems unlikely that anyone needing treatment would avoid it because of that, and in any case if they need treatment they may not be in a position to make the choice. The differing statistics are probably not down to local attitude/enforcement but more likely due to relative quality of the product in the market, the level of consumption, and quite possibly due to user knowledge and levels of treatment in the case of problems. The deaths statistic is also pretty worthless in itself (especially relative to aspirin) as many people don't die, but just end up damaged. There are facilities local to me filled with residents who did themselves permanent & serious harm but didn't actually die.
Re: 'assume consent' organ donation; I'm not so sure the problem is that you donate your organs after you die, rather that you could end up dead because you'd be useful as a donor!
Consider that a decision may be made for treatment to be modified or withdrawn to make you a better donor, even if this has negative consequences for you.
Consider that they don't tend to salvage bits in the morgue, rather you're harvested when still nice & warm, and preferably still breathing.
Also consider the likely impact of hospitals being set targets for obtaining 'donated' organs - what exactly would be the most likely thing for people to do to hit their targets given that providing the best treatment for individual patients no longer seems to be a particular priority?
Personally I think it would be better to encourage the current voluntary system to be adopted by more people than to change the fundamental concept.
An advertising campaign could be useful, as could some sort of sign up campaign e.g in supermarkets.
We could consider the impact on the likelihood of organs being donated if things were modified so that tax-free cash was given to the estate of the donor, instead of the current situation of all sorts of people benefiting financially except the initial suppliers! Though of course this gives relatives an incentive to see you dead (on top of the rest of your estate).