Perhaps the reference to testing is because if it were free, and just as necessary as a high school diploma for jobs, there would be so many students that the system would be overwhelmed, therefore the necessity of limiting spots. And since upper income kids generally are better educated and have more resources and parental help, they would test better and it would end up to be a system where the poor pay for the wealthier to go to college for free.
Testing and making life decisions when people are young would be a huge mistake for us.