Well in manga the author tends to forget assaults like that actually makes kids either trampled on by others, or makes them cruel. Only a very small % can naturally resist the main two outcomes. With that said, I look at it as discipline shorthand, there isn't enough time to show a proper way or recount how kids and adults would behave in the setting they are in, it's usually so far off. (like 8 year olds having the thought process/strategy of an veteran adult... just not happening...)
In america it wouldn't be the worse thing in the world for parents to discipline their kids, even slightly to harshly over not being there period (single moms and dads have it rough, and the children suffer), my generation is proof of this.