But how about spain, france & the UK?
They tend to cost magnitudes more in common law countries (USA, Canada, UK, Australia, NZ. This is generally down to the land and legal costs, with the dispute framework becoming much more expensive. Land and property rights are much more extensively protected in common law countries.
While we're guessing, this may just be due to the very special environment that is Manhattan. It's been a few years since I read about it, but I seem to remember that they had to fight some quite unusual challenges, including skyscrapers, the constant influx of water, and both granite and basically liquid sediments. Manhattan probably also has an insane amount od existing, badly documented underground infrastructure.