If I recall correctly, this was how universal secondary education came about (at least in Australia). Initially secondary education was available only through p

If I recall correctly, this was how universal secondary education came about (at least in Australia). Initially secondary education was available only through private schools (including religious). As demand for skilled workers rose, free public education was extended from primary to secondary education to meet the demand from employers. The same justification could easily be applied today with regard to tertiary education. Maybe this could be implemented by giving all people a three year 'credit' for tertiary education that can be used as and when they please. Note that I am not suggesting that tertiary education should be compulsory.