If idiots are sending sensitive data unencrypted so that other idiots can intercept it, meh.
If Google intercepted encrypted data and decrypted it, then I'd have a problem. However, if you have WiFi router broadcasting its identity (I do), you are inviting people to recognize and record information about your router. To me, that includes Google. If you don't want to broadcast that information, there is a mode that does not broadcast the network ID, but simply listens for requests from people who already know its name.
If folks choose not to use encryption and choose to allow their router to broadcast its identity (I broadcast openly but encrypt data), then IMO, the WiFi signals are readily accessible to the public who almost all have devices and software that can routinely read that data. It ain't that hard.
Google is nosy and intrusive. However, in this case, they looked at a naked lady voluntarily standing in a window. They weren't sneaking around in the bushes and peeping.