Private schools dont have as much funding as public schools.
Private schools have larger Student to Teacher ratio meaning it is harder for teachers to teach more kids.
Most of private schools are religious so most the tutition you pay goes to the religion and then the school gets a small portition which is barely enough to run the school.
Also private schools don't get as many discounts on learning tools and excersise equipment.
Half the time a they are porely run.
And also private schools don't pay the teachers as much so the teachers a private schools are either very religious and smart or won't be hired by anybody else. Most of the time it is the 2nd 1