Don't tell me what to do

It's a basic human principle...we don't like to be told what to do. I don't know why that is, maybe some psychology major can explain it to me sometime. An older woman walked up to me and the kids at Target this morning. I was in the floor with Ava trying various sandals on her foot while keeping an eye on Nate in the cart above me. She came over to see Nate (I think he was smiling at her) and was aghast to find that he wasn't buckled in. "Is there no buckle in the cart...?" she started, then after spying the dangling strap, "You need to buckle him in. He looks like he could wiggle out easily. That would be a horrible fall." I glanced up and mumbled thanks and returned my attention to Ava. He did look really wiggly at the moment, and I was hurrying to finish with Ava so we could get rolling again since he sits still when the cart is moving. I had my eye on him. I was within touching, and/or catching distance in worst case scenario. He's been my baby for the last 15 months and I know how he behaves in shopping carts and how a buckle isn't going to stop him if he really wants to get out, which I can see coming a mile away. I was really irritated with this woman for telling me what to do. She probably imagines us in a home where I barely keep the children fed and beat them every night since what kind of mother wouldn't buckle her baby into the shopping cart for heaven's sake? It shouldn't have bugged me so much...perhaps it's rooted in a desire to be seen as perfect even by strangers whose opinion isn't even important. Maybe it's a sharp dislike of criticism. I don't know.