Are there evidence it is really happening? Which open wifi network are left in residencial neighborhood? My neighbors aren't tech savy yet they use the wifi configured provided with the router which has a passphrase. I believe even in McDonalds you get the wifi password only upon purchase in the receipt. Most open networks I still encounter are in big stores such as IKEA or airports and you still have to register to connect. I doubt the signal woukd reach even the closest houses anyway.
> Which open wifi network are left in residencial neighborhood?
Some neighborhoods are mixed use. Some residences are in dense buildings. Some people configured guest networks with no password. Some ISPs made their home gateways captive portal access points.
Having a guest network doesn't mean it is open. It can just means you have a passphrase that is different than other home devices and that you may be isolating them in a separate VLAN.
I would never run an open network on my home connection, there are way too many legal risks unless you can log who is connect to it and when.
