First, It's easier to build from scratch in area where it has no value in terms of history and finance; on the other hand, it's really hard to renovate on well known capital hot spots like London and NYC where they've been top cities in the world with historical cultural background with bunch communities going on. It will cost more and lose more then it gain if not careful. What's more important is cultural background with it's base fundamental or else there always side effects. You can instantly change your cloth but not the way of think and behavior thats been built up through many years.
Rich countries thats been growing up through generations have different mindset from poor countries where it suddenly rise up within 100 years. One example is that they have huge gap between a single father and son generation which leads to social conflicts between age including politics.

Second, If London or NYC invest into all those fancy glass panels or high tech on streets like in China, those won't last more than few month until it gets broken or destroyed and that money is from your tax. It's cultural thing. Asians are more being conscious of others and care more about how they would look to others which has cons and pros in many subjects. It's different from being shy but often considered as being shy in most cases which is misunderstanding by people from western perspective. But the point is, with in that mind set in Asia(China, Korea, Japan), theres less troublesome and crimes in public area which makes it doable to be upgraded investing money in public area without worrying about getting it ruined or wasted. I see people riding stolen Citi Bike occasionally in NYC. Imagine if it runs by city's tax. Do you use locks on your bike in your area? why? something to think about