Only if your expectation is that mailing your thoughts on what amounts to a digital postcard that passes through dozens of hands before it arrives to the destination is private.

What I meant was that most people assume it is secure. I mean only a few % at most has any clue how email works. I suspect most of my colleagues who has been working as developers for decades don't know that email may pass through dozens of hands. Of course if you know how it works you know its not secure, but very few people knows how it works.