However, selling data to Google still seems like a bad idea. Things that are off mission and the point is to make money are just a distraction with no good purpose that's going to make the post office be greedy instead of just focusing on delivering the mail.

I could maybe agree that there was some value in having a public set of streetview like images (which is the more likely thing they'd do, not sell it to Google or whomever which would just be terrible), but it also seems deeply creepy. Then again, Google is already doing it so I suppose there's an argument that at least this way it's public domain.