Instead of thinking "We can't think of a less intrusive way, so deal with it", how about "We can't think of a less intrusive way, so let's not do it until we do".
Turning WiFi SSIDs in to location data doesn't track people directly, but it does enable the mass surveillance of people's devices, and that's something that's quite reasonable to opt out of.
cite?
But it's not just that is it? If you log in to a google site from that publicly broadcast BSSID, you will get tracked by association, even if you have your location tracking turned off.
I wouldn't bet against Google being capable of exfiltrating BSSIDs via their broad swathe of 'Google Services' most Android devices are running (and probably most iOS devices too).
Both have location privacy controls that govern that, and there's no particular reason to believe they ignore them.
(And Apple might be too, but they've got different motivations and incentives around iOS user privacy that Google for Android users...)
Apple is also collecting & phoning home all SSIDs with a GPS location that they come across, for example. So is Mozilla for that matter, and Mozilla also uses the same _nomap suffix as Google does ( https://location.services.mozilla.com/optout ). It's how browsers on laptops are able to get a location, which is also true on again both Apple & Microsoft devices as well.
So no, Google can't just opt to not do this at all. Not if they want to be competitive. The entire ecosystem could collectively decide to not build an SSID location database at all, but since SSIDs are not identifying this is going to be a struggle to justify.