Why am I writing about this again?
Some parents do not pay attention to the rude behavior of their children. Socially unacceptable actions of their children are repeated and become a habit. Such children become rude and arrogant people. Luckily, there aren’t many parents like that.
In my experience, most parents take children's outbursts too dramatically and punish them too strictly fearing they would become people such as I described in the preceding paragraph. If the children were provoked by something and reacted inappropriately, severe punishment creates defiance and they don't see realize their error, but feel misunderstood and probably are likely to react in a similar manner next time.