That’s true, which is why the article mentions one of the things googlers are doing is using their phone as a hotspot.
Y’see the phone gets it’s internet from the cell tower. It then passes the internet to the laptop via a local (i.e. 2 feet) wifi or bluetooth connection.
That’s an entirely different thing than enterprise-wide wifi. And if the building was blocking cell phone signals - well, first of all I’d be impressed, and secondly they would tear it down.