We can probably agree that an engineer or a doctor provides value to society and thus could logically expect to have his or her education compensated because of that value provided.
(Of course, the other side of the coin is that since the degree also has value to the individual, they ought to be willing to pay for it. )
Now, change the major from engineering or medicine to social studies. Obviously, society needs a FEW social scientists, but nowhere’s near the number that are currently being produced; and if that education were to be free, the number of graduates in this and other nonrigorous fields of marginal value would be staggering.
Why should the taxpayer pay so baristas are more educated?