Grown - ups are experienced. More experienced than children. I think that grown-ups only want good of children because they love them. But as being small and having lack of experience the children can not get it why grown ups are always telling him wrong and right.
Yes, it is important that they teach children good manners, and how to behave in public. It is important to make children civilized from childhood. So, that they become civilized citizens. But giving them extra pressure is not correct. They are children of course !