[billybob]

To me, this sounds a lot like "you didn't bother to lock the door, so obviously it's legal for me to come in," or even "you used a lock that's easily picked" with the same conclusion.

If I'm a non-technical person, I send an email, I address it to a single person, expressing my expectation that only that person will read it. Just because someone CAN violate that privacy doesn't mean they should be allowed to. Just like when I have a private conversation in my house with the door closed, I'm expressing an expectation of privacy. Just because someone CAN bounce laser beams off my windows, read the vibrations, and reconstruct the sound waves doesn't give them the right to do so at will.