This is ridiculously unfair. we all get the same education, which is a good or service, so why would some have to pay more than others. Its the equivalent of changing VAT so that richer people have to pay more for the same goods as poorer people.
The reasoning is also as flawed. Lets say two people do the same degree. One works harder than the other and therefore gets a better job. under the new grad tax proposal, the one that worked harder then has to pay more for the same education. Its a tax on cognitive ability and work ethic. Now tell me, how is that fair?
This may be extreme but there is more than a hint of communism here, that everyone should be equal no matter how much more effort some people put in than others