I've been wondering about what you said there Chuck. Perhaps my original analogy was flawed.
It's wrong to go through an open door of a house because, if anything, it is trespassing. A wi-fi router broadcasts on a public radio spectrum though, therefore anybody who has a wireless network is "borrowing" the frequency/band used in that localised area, right? They don't own the airwaves in the same way they would own the property.
Doesn't that mean then that, if the network is broadcast, open an unsecured, that is effectively becomes public? If so, then if I access it routinely, rather than with intent, is it still illegal? An open door on a house requires me to walk through it, whereas an unsecured wireless network is literally transmitted into my property.
Or am I just arguing semantics?