I agree that this is a larger and more complex puzzle, which is in fact why I avoided addressing it in my post. That said, I want to address some of your points, with which I mostly agree, individually.
Regarding 1), this is true but, all else equal, you’d think that employers would still have incentives to find cheaper or quicker work-arounds for extracting the same signal (see my discussion of Google hiring directly out of high school in the post). I suspect they don’t because of the other reasons you mention in your comment.
I agree that 3) and 4) play large roles that are hard to model in economics studies. While I haven’t read it, I wonder if Tyler Cowen’s “The Complacent Class” discusses this.
I agree that this is a larger and more complex puzzle, which is in fact why I avoided addressing it in my post. That said, I want to address some of your points, with which I mostly agree, individually.
Regarding 1), this is true but, all else equal, you’d think that employers would still have incentives to find cheaper or quicker work-arounds for extracting the same signal (see my discussion of Google hiring directly out of high school in the post). I suspect they don’t because of the other reasons you mention in your comment.
I agree that 3) and 4) play large roles that are hard to model in economics studies. While I haven’t read it, I wonder if Tyler Cowen’s “The Complacent Class” discusses this.