Upon my return to North America after some years residing abroad, I was greeted with a few pieces of good news. One was that wizards working behind the name "xfinity" had conspired to bring free wifi to much of the region.
They require only that you change your MAC address every hour, e.g. with the commands
sudo stop network-manager
sudo macchanger -r wlan0
sudo start network-manager
and that you provide an unverified email and zip code.
(details of those commands will change depending on your system).
I raise my mug to you who have turned every home router into a provider for those in need. Thank you!