That's unfair. I had a child like that, but it looks to me as though this young man behaved better than mine usually did. It was as if any type of public attention just made her turn on a switch. She was consistently disciplined and loved, but I had to put up with comments like yours for years. Some children are just like that. Her terrible twos lasted at least 10 years and it was challenge to see if I would survive. I did, and miraculously, so did she. By the time she was a teen-age, I had a very well-adjusted and well-behaved child. I watched other parents struggle through their childs' teens. Mine was a breeze. Children are just extremely different.
If your kid had my Dad for a father, she would have behaved like an angel in public when he was within eyesight. Guaranteed!