I kinda disagree with the London example. There's a lot more contral planning and long term planning by the government here. In a country like UK, for London, not as much because politics get in the way.
If you are a good central planner, you want to spread out the density a lot more. You also want to make things far more connected because you don't want over crowding all in the central area.
Leave all that to the private sector, and all the businesses and population will automatically grativate towards the centre and just make it super crowded. Leave it to the politicans only, and you get the same thing (because the companies there can pay the most), plus some special interest groups on top of that.
So, the outlying areas automatically get the least funding and hence the least
amount of infrastructure built up.
Singapore has far more central planning. We already have circle line being done even before these other lines. Cities like Melbourne actually discontinued their equivalent circle lines because the traffic didn't justify the expense. But Singapore doesn't just build the MRT infrastructure, it also uses its HDB
policies, release of new land to ensure that other non-city centres are formed.
Tampines 20 years ago was a backwater nothing. Tampines today is a bustling self contained newtown all by itself. So, because of this kind of difference, I
think the prices will be a lot closer. Just my 2 cents.