Because they don't need one. They just send a polite email asking for everything on Person X and they get an email back with EVERYTHING that person's ever done on any of Google's services.

Problem solved. No Backdoor or Warrant needed.

If one country required non disclosure of backdoors and another requires disclosure, who wins?

Yeh, good.
Hopefully they will realise what a farce OSA is as well, considering the skyrocketing VPN usage!