The Need for Private Education

I wonder if J. Gresham Machen could see into the future because what he said about public schools in 1933 could be (and is) being said today.  From J. Gresham Machen: Selected Shorter Writings:

The only way in which a state-controlled school can be kept even relatively healthy is through the absolutely free possibility of competition by private schools and church schools; if it once becomes monopolistic, it is the most effective engine of tyranny and intellectual stagnation that has yet been devised.

HT: John Piper

Are we not seeing this today?  Though home schools in most states, legally are considered “private schools.”  I would add that here since it wasn’t very prevalent in Machen’s day.