It's no coincidence that every sign of showing frustration or confusion is considered disrespectful when a child does it to a parent.
A child raising their voice, not enough to strike terror and not even enough to startle, but barely enough to show frustration, is considered disrespectful. Meanwhile, in a typical conversation between two adults, the same amount of voice-raising would happen on a regular basis and people would think nothing of it.
A child rolling their eyes, which is caused by confusion and can easily be involuntary, is considered disrespectful.
If a child found another way to express confusion or frustration, that would eventually be added to the list of things that are considered disrespectful.
The goal is to make it so the child is afraid to show confusion or frustration. Then, when the child shows no confusion or frustration, the parent can pretend that the child is happy and that the parent is doing a good job. The parent can then pat themself on the back and congratulate themself for a job well done while never having to actually care what effect they have on the child.
