In ancient Indian education system there was eligibility test to attain from knowledge from teacher. Teacher was giving some test and based on result the disciple was getting knowledge from him. In modern times it is become so essential as everyone have perception that knowledge is attainable as they have money. Here is small story that narrates same.
There was teacher who was famous for his voice and charming personality as well. Once his village high ranked person came to his school and took admission for his daughter. He wanted to his daughter to learn music. Initially guru not taken test as he was having belief that everyone should get opportunity to gain knowledge. High rank guy had predetermined that after six months she can sing excellently. Initial classes were not up to the mark due to her voice modulation. She was not practicing but regular to class. The day came when high rank man expectation period ends so he wanted to listen her melodious voice but her modulation still needs to be fit into pitch. He was annoyed and starting to question teacher that I have given so much time and money as well where I have not seen results.
Now the question is who is wrong place?
Teacher's thought everyone needs opportunity to learn no need of eligibility test or student who does not practice even though she is keen interest into music or high rank in village had high expectation on her daughter
Sometimes an eligibility test is required as talent are not default for all. Some skills need training and some of them are inbuilt which needs polish from coach.