The article contains no evidence of a government-operated network of listening microphones in the Bay area. It deals with one incident using a specific piece of surveillance gear.
What we actually know is this:
An FBI agent was attempting to bust two individuals suspected of a bid-fixing scheme.
This FBI agent then placed two recording devices in a light fixture and another at the bus stop nearest the courthouse.
After the surveillance recorded enough incriminating evidence, the FBI/DOJ sought to introduce the recordings at trial.
All else was rank speculation by a former FBI employee named Jeff Harp.
He also stated, "If you’re going to conduct criminal activity, do it in the privacy of your own home... that was the original intention of the Fourth Amendment," which makes me question his grasp of the constitution, and thus his reliability as an expert.