Bryan's education complaint

Bryan Caplan is on a kick against formal education, he makes good points, but I discuss search costs.  Here is an example of his, my comment on the bottom:

Almost everyone pays lip service to the glories of education, but actions speak louder than words. Ponder this: If a student wants to study at Princeton, he doesn't really need to apply or pay tuition. He can simply show up and start taking classes. As a professor, I assure you that we make near-zero effort to stop unofficial education; indeed, the rare, earnestly curious student touches our hearts. At the end of four years at Princeton, though, the guerrilla student would lack one precious thing: a diploma. The fact that almost no one tries this route -- saving hundreds of thousands of dollars along the way -- is a strong sign that students understand the value of certification over actual learning.

Let's compare costs.  A STEM college grad will earn 100 K and up to start.  Over th lifetime career, what are the search costs between the undocumented grad and the documented grad? 

The undocumented worker needs and extensive conversation and review to tease out all the work done on college.   Imagine if all these Princeton and Yale trained college kids had no document, the labor search time  goes up and equates to the value of the document.  Bryan neglects the sorting value of formal diplomas.