Really? Google has the knowledge of where the network is, who has access to it, and what the password is. Remember also that WiFi networks are a shared resource and often provide access to internal corporate data.

From a governmental law enforcement perspective, that's an incredibly valuable trove of data. Instant network backdoors, likely with no physical entry required.

Even if you're not using the data to sniff networks, you can use it to build detailed relationship graphs between people and places.