Actually...
As a ham radio operator, I can operate WiFi at higher power levels than the normal routers come with, and I can NOT use encryption to prevent others from using the system.
(I COULD lock out all but my given MAC addresses, and there are a few other things I can do)....But I MUST ID my wifi with my callsign for connection and identification purposes.
So, theoretically, if I open mine up like that for Ham use, I can’t BLOCK it (to other hams) and I can’t encrypt it to prevent NON hams from using it (if they can get in).
That’s in the FCC regs. So, it isn’t stealing if I leave my stuff open. On the other hand if I leave my car unlocked and someone takes the car, then... it’s a stolen vehicle.
Whether it's stealing solely depends on your intent, and it's up to the other person to determine that. Leaving WiFi open for your neighbors is getting popular, and routers have been made that have two firewalled sides for your security, one for you and one for the free WiFi you're providing, both using the same broadband connection. I believe the British phone company is even encouraging people to have open WiFi so there will be more coverage for mobile devices.
This will drive the RIAA and others nuts when it gets more popular, as going by the IP address (if using NAT) would mean nothing anymore.
But when that's popular we will have to have a shift in thinking and law to what the author thinks: leaving it open is implicit license to use it. We already do this for the private property most of us visit every day, such as stores and restaurants. If we don't do this you could accidentally break the law 20 times by driving down the road with your iPhone.
That's not true. There are plenty of closed 2-meter repeaters that won't allow access unless you have paid a club membership. You can't encrypt it, but like you said, you can restrict access via MAC filtering or other means. THAT is legal.