If you think student/teacher relationships are "hierarchies" by default then you have a severe distortion of how reality works. You can teach someone something without exerting undue power and influence over them. Telling someone a technique to make washing dishes easier doesn't mean I am an authority over them. Lol.
"If you do X for me, I will give you Y in exchange"
The root of all eeeeevil capitalist trade endorsed by the ancaps you malign. Why do you condemn this?
Again, your first principles mean nothing. That isn't what capitalism is, it's one small aspect that relates to it. Pretending that markets are inherently capitalist is silly and unimaginative. We had markets during feudalism.
The teacher/student relationship is definitely a hierarchy, and one of immense power disparity, yet it is not coercive.
We did have markets during feudalism. And feudalism plundered those markets, as all government systems do. Feudalism obviously wasn't capitalism. Feudal lords plundered land, food, and money. So do governments and their corporate cronies today. But this is all obviously in opposition to Lockean property rights and free trade, even though that is also commonly called "capitalism."
I don't know what world you live in, but if one person had all the knowledge, I'd see your point. This is 2019, we have the internet, and we have millions of people willing to teach. Your fantasy scenario of teaching being a natural hierarchy doesn't make sense in 2019. Maybe if it were 1208, maybe, but this isn't a Minecraft server that we refreshed a week ago, this is the real world.