[@Pathfinder]

People are more compliant when they believe they are having free will. If you think about it they don't have as much as they think. They are stuck to one class and made to believe they can be nothing more than what they are. That there are no possiblities for a different outcome.

Look at Peridot for example. 
She was told that next generation Peridot's and or other lower gems did not have powers and thus they needed tech. She never even tried to see if she did indeed have a power because it was just how it was in her eyes. She didn't even entertain the idea that she should try until Amythest and Steven said that she could do transformation of she just tried hard enough and thus her tech powers were discovered.