DrZoidberg
Contributor
Death penalty is another one of those that has to do with how late the country industrialised. After industrialisation (ie shift away from a predominantly agrarian economy) it'll take about 150 - 200 years or so. There's a whole bunch of these similar activities. The reason USA still has the death penalty can be explained by the fact that they industrialised later than Europe. And it'll eventually go away.
When the US started to industrialise, New Zealand wasn't yet.
There's individual variation. But there's a whole bunch of social changes that come as part of the post-industrial package. Death penalty tends to be one of them. The fact that New Zealand is ahead of the curve doesn't disprove this. There's a whole bunch of these. Especially when it comes to things surrounding sexuality or marriage. Post-industrial countries tend to see all life as sacred, precious and worthy of respect just because it exists. Agrarian economies tend to see life as cheap, disposable and value is based on what the person contributes to the community. This is reflected in the social values.
There's more. Agrarian economies are surrounded around the family unit with one head in total control of the families economy. And all the dependents completely at the mercy of this guardian. There's a very obvious hierarchy in society. Everybody has a very rigid duty for their station. Who cares if you're gay? Just get married with a woman anyway and produce off spring. You don't have to like it. Just do it and think of England. Duty.
Industrial economies only have a bunch of nominally free agents who are free to arrange themselves in whatever way suit them individually. And if it doesn't suit them any longer they break the unit.
This to is reflected in social values. The individual and their freedoms is sacred in the post-industrial society. It just isn't in agrarian economies. And these social values is a direct result of the economy. Agrarian economies are very sensitive for change. There's just so much land and it's in nobody's interest to upset the situation. Complete opposite for an industrial economy. The freer the agents the greater the economic value for society as a whole.
It can also be seen in religion. There's a liberalisation of religion that follows this. Initially religion gets increasingly fundamentalist. One explanation is that as the old social structures are torn apart people cling all the more to what vestiges exist of the old. But eventually the fundamentalist religions rapidly collapse and are replaced by liberal religion. This has happened in every western country so far. And Japan. Karen Armstrong explains it really well in her "Battle for God". This explains Muslim fundamentalism in the Middle-East. The radicalisation of Islam nicely follow the pattern of religious extremism in the west. 50-60 years after industrialisation it comes... and then will collapse. So I'm pretty sure that's what's going to happen to ISIS and Iran.
As industrialisation grows stronger and it's values spread in society the more intrinsic human value is upgraded. Eventually it's seen as barbaric to execute people. So it ceases.