I remember a children's class in the Aikido dojo where a parent hit the child on the head because the child forgot to bow at the entrance of the dojo. On another occasion a child was yelled at because he could not tie his obi. One parent went as far as to call his child names like stupid and idiot. All examples of parents using control and manipulation the make the child do something that see as important.
But making the decision for a child to practice aikido is not a form of manipulation? Why not soccer? or baseball? Knitting? When I talk to parents, they ultimately make the decision to enroll a child in aikido; predominantly, this decision is made because the parent believes enrollment is in the best interest of the child.
We grant authority to manipulate others when we feel that authority will better serve us. Adults have authority over children, police have authority over civilians, etc. This authority is granted, that implies we do hold some power to choose who can affect us. Some of us are better or worse at granting authority, for a myriad of reasons. Ultimately, we are all susceptible to some form of manipulation - that is why Super Bowl ads cost like $1,000,000/minute or something crazy...