Strangers giving unwanted advice

Whyyyy is it that when people see a baby in public they feel the need to give ALL of their advice. I took my baby to 2 stores w me today because I was on a hunt for new towels and people think they can really just do what they want. My cashier reached over the counter to touch his back! Now I have no issue w small talk and asking how old he is and they always say how cute, that's fine! But he was chewing on his fingers like he does 24/7 and I get oh you better be careful with that! Or a lady talking about her neighbors newborn & she was complaining that the mom holds her baby all the time. She said and it's not her first child she should know better by now! And asking me if I'm breastfeeding. And OH HES HUNGRY. Like no my boy just ALWAYS has his hands in his mouth. He has at least 8 lil teethbuds going on in there he likes to chew on things 😂 Anyways delayed irritation bc it's bugging me so much more now hours later. I just don't get it ? Is it because I'm younger or does everyone get the unsolicited advice from strangers 🙄 Asking for advice is different than just trying to stand in line & politely smiling at someone imo