Problems with private schools

There were a few good comments on my Guardian piece the other week that are worth highlighting.

One of the most most important points is that when private schools get the same results as public schools for a fraction of the cost, they are still getting woefully bad, unacceptably poor learning outcomes.

Suvojit and Heather raise the issue that results are only going to be comparable when teacher effort can substitute for training - this is possible at lower grades but likely to get more difficult at higher grades with older children and more difficult material.

But neither of these for me damage the case for directly supporting private primary schools if they are still doing the same job substantially cheaper.

A criticism that might do this is one that Anurag Behar (CEO of the Azim Premji Foundation, a leading organisation on education research) makes in a Mint column, which strikes at the heart of the private school business model. His argument is that private school teachers only accept such low wages because they are "queueing" for a government teacher job.

It’s clear that the salaries of teachers in most such private schools are very low, bordering on the exploitative. The reasons why they get teachers at these salaries are fairly simple. Most of those who join private schools as teachers are those who are waiting and trying to join government schools. Since recruitment of government teachers has its own pace and scale (though it has become “cleaner” in many states), many keep waiting and trying for years, and it’s this lot that largely feeds the private schools. Eventually of those who don’t make it to the government system, many leave teaching to do other things, which is not surprising, given their salaries.

One reason to doubt this story is that if those private school teachers are unqualified then they aren't eligible for a government teacher job. But I'm open to persuasion if there is any data here?