In every culture you get these sort of people.
In England Ellie and I were once having a nice romantic time swinging on some swings in a park, when a grumpy old man came up to us and said. "Hey! Hey! Do you know those are only for children!?". He had the sort of deep self righteousness that English are so good at, but I could tell this "Justice Warrior" was a wimp. He could see from our laughter and good time that we were nice people, who might listen to him, an ideal target to boost his pride. He would never have dared approach the young teenagers who would also often use the swings. Technically, this part of the park was for children, so he was technically right, that is, legalistically right, but not morally right at all. There were no children for miles around, and the swings were the normal heavy duty ones that anyone can use. If there had of been any children around, we would have certainly stopped swinging and let them use their park.
In China we have an arrangement with our local shop where we order in bulk and he delivers it to our door. He gets good business from us because of this. He is happy and we are happy.
One time one of our neighbors saw him carrying the good and criticized us for making him do that.
I guess these sorts of people are just bored and feel powerless in their life, otherwise they wouldn't see the need to be such busybodies.