THIS. I've noticed this my whole life, and I know lots of other women have too. J. Victoria writes about it brilliantly, I wonder if black women get it more aggressively? Entirely possible. I do know that the absence of a vacant smile and the presence of a book in your hand can cause quite a stir in some males' psyches.
Either way, as J. Victoria notes, I'm not telling anyone else how to look, feel or express themselves. It is unbelievably condescending to tell women to 'smile!' constantly. What the fuck for? I will smile when I goddamn want to. It raises my hackles every time. Thankfully as I get older it seems to be happening less. Either I've mellowed (doubtful) or no one gives a shit anymore if I'm smiling or not! Hallelujah.