No. It couldn't. You certainly could make a 4-year degrees ostensibly an extension of high-school - where the school is fully paid for - and some countries do do that. There's still opportunity cost of not earning an income for those 4 years. There's no getting around that.
>One could also imagine a hypothetical culture that does not prioritize earnings so highly, and could value other attributes of service or community more highly than earning high incomes, but let's not get too crazy here...
Plenty of people do that already. In fact, most people balance out income with other life goals whether it's through career choices, deciding to stay home and raise kids, or even deciding to stay in some city because your entire family is there. So I don't know what you mean by a "hypothetical culture that does not prioritize earnings so highly", everyone already makes those considerations and though income is important, for most people it is not the most important thing.
>At the highest tier, the expensive schools protect the oligarchy by keeping their children in different social spheres than the rest of the population. At the level of state schools, it's a zero sum game that people feel forced to enter because their ability to make a living is otherwise severely impaired.
I don't agree with that characterization at all. For one thing, state schools provide quality education (that is as good as any high-priced ivy league school). I'm not sure what the zero sum game you're referring to is. Many people do see university as a vocational institution and what's wrong with that? Making Nobody is forcing anybody to do anything, and most people are excited about becoming teachers, or software developers, lawyers, nurses or architects.