I saw this PBS debate. The big focus seemed to be how do we get more of our people to get college degrees than other countries.
For what purpose? If all you want is more degrees you can just make college easier cheaper and more enjoyable. But that would destroy the value of the signal. Notice there is no discussion of what skills and knowledge would help people most and what is the best way to get it to the people who need it most.
I think the myth busters TV show is educational. Many games computer and others exercise thinking. History channel teaches history. PBS teaches cooking and gardening but none of these produces a signal and so the are not discussed when in debates like above. I consider this proof that schooling is primarily signaling.
Addition evidence that school in more about signaling/credentials verses education:
Most college professors lack much work experience
Midwives and PA's get the similar outcomes as doctors
If 16 years of education is better for college people can we be sure that it is not better for carpenters?
Sometimes it is better to be the best plumber than the worst lawyer.