It's a great example of the breakdown in understanding of a system. People envision WiFi as a wireless pipe or cable whereas in reality you're broadcasting in every direction out to infinity.
When reality doesn't match peoples' expectations they legislate a 'fix' (making listening illegal) rather than fixing the fundamental technical issue (with encryption, randomized IDs, etc).
I think that's argued a little differently. Rain you collect from your roof is water removed from a watershed which has an impact on everything living in that environment. You aren't allowed to burn your trash in your yard and pollute the 'public' air either, for example.
> It may be illegal to monitor networks for MAC addresses
I use promiscuous mode to monitor and send alerts about everybody with a wifi active phone that comes onto my property. I also have cameras and motion sensors. It's not illegal and if it's made illegal I'll keep doing it because I have an intrinsic fundamental human right to protect my property.