Dear lady behind me in the check out counter,
I fully understand that you are being sweet and friendly, but persistently trying to talk to my introverted 3-year-old as he squirmed in the shopping cart seat makes us all uncomfortable. I politely told you he was shy, but you never let up. You caught him on a good day – he didn’t start crying as a result of your constant attention. But once you kept rubbing his back while saying hello, he began trying to climb out of the cart to escape you. I know you had no ill-intention, but please understand that not all children are extroverts. My oldest would have talked to you long enough to see you in your grave, but my youngest is an introvert to people he doesn’t know. 
Once he knows you, really really knows you over the course of several months, he turns into the outgoing child you expect all children to be. However, to strangers, he simply wants to hide or bury himself in my arms to try to disappear. This isn’t a result of some childhood trauma. It’s not a lack of parenting skills to force him to talk to someone who makes him uncomfortable. After all, aren’t we supposed to drum “don’t talk to strangers” into kids these days? It’s simply his personality.
He is shy. He’s an introvert. Nothing you do or say will change that. I know you didn’t know that to begin with, but once I tell you he is shy, and you see him struggling to get away from your attention, even down to trying to physically escape when you touch his back, that should be a clue for you that he’s not that outgoing kid society seems to expect. So please, stop trying to touch him and just let him be.
Thank you.
The Ragged Mommy 