Well, the truth is we just don't often see them in the neighborhood any more - at least not where I have been living the last 2 decades. They are much like dinosaurs - something from the past!
I am talking the blue box with the postal symbol on it, not the slot in your mailbox cluster.
And, now I have one about 2 blocks from my new place and they actually pick up once a day, six days a week! Yippeee!