School counsellors can have hundreds and hundreds of students assigned to them. A private one can keep his/her client list to a humanly possible to serve number.

My son's school has about 3000 students. Over 600 seniors (yeah they lose a bunch between freshman year and senior year). Case load for the college counselor is impossible. She has many assemblies and meetings after school. I can't imagine you get much one on one help.

I for one am glad private ones exist. Not sure we will employ one. But glad I have the option and am savvy enough to find a good one.