There is also a discussion regarding tuition fees related matters. Up to now the majority of the German universities are regulated by the state.

No tuition fees: That is fair for poor students who want to yield a degree at university. But the point that all tax payers are contributing to the money paid by the state to the universities. But only few lower income families enter universities as Richard said. As once they get into university they often get a good job and they do not belong to the poor families for no longer. But in general not having tuition fee may encourage more high-school students to start studying and thus contributing to skill level of their country, especially as most of the jobs are "high-level"-skill-based. Loads of students in US do not issue a master because they are afraid of getter deeper into dept. Though most universities offer statistics to students where their typical graduates end up and thus it turns out to be worth investing into your education.

Tuitions fees: Arguments can be reversed. Only those people who study should pay fees because only they will benefit later. Why should low income family pay universities with their taxes though they will never attend them? That is because some smart people establish a start-up and they need some "average" people to do administration stuff for example. But as more work is done by computers and robots that argument does not always work.

There might be some poor students not being able to attend but you cannot optimize all parameters or you introduce a huge scholarship system as partially available in US. It seems US top-notch universities have a mix of students where some of them seem to pay loads of tuition fees whereas other contribute to the research reputation of the university. Though it should be noted that quite often tuition fees only contribute a minor part to the university budget.

It should be noted in the discussion of tuition that the US has more top universities than any other country in the world, and that a great many people who have researched this issue suggest that the tuition system is a big part of the reason this is true. (Compare that with the high school and middle school systems, in which it is not clear, and probably not even true, that the US is the best in the world - most middle and high schools in the US are public, i.e., supported by taxpayers.)