Have the Supertrees already been built?
They are part of Gardens by the Bay - a botanical park - so they are more of a demonstration of the technology. If they are going to get deployed anywhere, Singapore would be the place.
Libertarian though I am, I have become convinced that no large city filled with fallible humans can be governed without imposition of a Lee Kwan Yew- or Rudy Giuliani-style benevolent dictatorship. An efficient and honest system for detention or deportation of undesirables is essential. Otherwise, criminals and deadbeats quickly game the system and overwhelm the good citizens.
Obama is trying to take this human failing national for political gain...and he's doing a damned good job.
RE: Have the Supertrees already been built?
I believe they already have.
See here:
http://www.nst.com.my/red/landscape-singapore-s-garden-of-eden-1.192225