When critics inveigh against private schools, they tend to pick on issues such as the following.
Everybody's Rich
Actually if you look at the beginnings of most private schools, you will discover that their original clientele were not children from wealthy families. Many of the founders of schools back in colonial times - the Phillips family, for example - saw education as the way forward for the infant democracy which was the United States. In order for the nation to survive it needed a literate, educated, proficient population. European crusaders like Dr. Maria Montessori and Rudolf Steiner - the founder of the Waldorf Schools movement - began their work among the poor and working classes. Their teachings captured the imagination of American middle and upper classes when their movements spread to the United States.
Over time as the schools expanded, they became highly prized for what they accomplished so very well, namely providing an excellent academic education, combined with sports and solid core values. Market forces conspired to drive the cost of education up. Social forces conspired to make private schools the place where the elite sent their children. In the 21st century egalitarian ideas once more have the upper hand. Private schools seek out and encourage applicants from every social and economic strata. Diversity rules. Not everybody who attends private school is rich.
Compulsory Sports
What's not to like about sports? Schooling throughout the centuries has always had a physical education component. Think Olympics. The ancient Romans