Read the dialog.
Bryan Caplan is the author if the book I reviewed. Probably I was over-supportive of Bryan's argument in the review, but I still side with him in this dialog.
I remember once tagging along to take a friend's son to his music class, there was another kid riding with us. My friend's son told the other kid "I go to more private classes than you do" . . . probably the other kid did not have the means for the expensive piano lessons, etc. This helped me realize that the whole private-classes-affair can degenerate into some kind of destructive competition among kids, let alone among parents.