What Are You Reading?

Strangers seem to think that if I'm holding a book that this is an invitation to speak.

I suppose they don't realize that I'm reading a book because I'd rather do that than speak to strangers.

Nobody walks up to a stranger with a cell phone or a laptop or a tablet and asks them what they're reading.  But people want to talk to me about whatever book I have, even when I'm sitting silently reading.  Somebody might try to look out of the corner of their eye at someone else's screen, but there is a presumption of privacy and the curiosity is not overt.

This isn't the case with a book.  "What book is that?"  Then they want to tell me about a book that they like.

I feel this is so random.  It's like walking up to someone I don't know and saying "You have a shirt on?  I have one on too!  My favorite shirt is green.  You should get a green shirt."