I'd really like to understand where you're coming from here, because I feel like we're talking past each other. I'll ignore the personal attacks, and hope you'll refrain from them in the future.
First of all, a misconception I really want to correct: I am talking about "no restrictions on what the young person chooses to do" (including what work they do, etc), not "at least they can go where they want". This seems pretty clearly different from "slavery" to me, and I'd really like to understand why you feel differently.
The way I see it, we have an adult who wants to learn a set of skills (and the argument over whether _that_ is the purpose of postsecondary education is a very important one, but the fact of the matter is that attempts at "universal college" seem to be driven by the "it will get you good jobs" motive, not by the "it will make you a more reflective and critical thinker" motive). Yes, they are young, but they are not a small child incapable of making decisions. And yes, I would support guardrails to prevent abusive contracts, not because they are young but because this stuff can be complicated and not everyone involved is in the top 5% in intelligence; those guardrails are sadly lacking in the current college funding setup in the US.
If you disagree on the basic premise so far, I'd like to understand where you disagree.
If you agree on what the goal is (teaching people skills), there are various ways to finance the acquisition of these skills. The ones I am aware of:
1) One could save up enough money to pay for the relevant lessons, then take the lessons. Or be earning enough money while taking the lessons; the "work your way through college" route. This has the chicken-and-egg problem of likely wanting the lessons to increase earning potential (though perhaps just to have a less-uncomfortable job, of course) and therefore lacking that earning potential, and hence ability to save, right now.
2) One could take out a loan to pay for the lessons now, with the goal of using the increased earning power to pay back the loan. This is the current US model, in large part. Especially for socioeconomically disadvantaged students. There are all sorts of well-known issues with this model.
3) One could rely on one's family/friends/whatever to finance the education. This is largely the historical university model pre-20th-century and is a big part of the model in the US for socioeconomically advantaged students. This model basically involves an intergenerational transfer plus an implied "pay it forward" obligation. In some families the obligation may be explicit (e.g. parents finance older children who then promise to help finance younger siblings). This model has obvious inequity problems.
4) One could rely on labor performed as part of the learning process to finance it. This is the historic apprentice/journeyman model. I think it's under-explored in many cases today, though internships _can_ be something along these lines. The mismatch between how much those pay and the actual costs of postsecondary education mean this model doesn't work very well typically.
5) One could rely on "the state" to finance education. This is similar to #3 except (1) it does not rely on accidents of birth and (2) the "pay it forward" obligation is compulsory, via taxes or a period of restricted work options after graduation (e.g. as practiced in the USSR). This model does well on fairness metrics, but I think it suffers from some serious incentive misalignment and resource misallocation issues. It can also be adversely affected by demographic trends (e.g. if the financing structure assumes population growth which then does not happen). Fundamentally, this is in fact equity financing, done by society at large.
6) Equity financing of some sort by non-state entities. This avoids some of the failure modes of option #3, in that financing is not based on parentage. It allows the time-shifting of expenses vs income all the models except #1 manage. It does involve a commitment of part of future income, as does option #2 and option #5 (albeit this last hides that commitment more). I believe it's preferable to option #2 because it builds in things like "your payments won't be too much to bear" by default, whereas option #2 requires hoop-jumping as soon as something doesn't work as expected.
There's an important discussion to be had between option #5 and option #6. I think that discussion is a valuable one, and I _think_ incentive effects can be better with option #6 and option #6 is more likely to lead to more flexible terms that can be better tailored to suit preferences. But I can also see state-funded fairly flexible programs; it really depends on how its set up. I would not be at all surprised if the tradeoff here varies widely by individual and by how non-corrupt and competent your government is.
I do think that option #6 is definitely a much better fit than options #1-4 for modern post-secondary education.
I also think that option #6 can be trialed, and even largely transitioned to, without needing to solve the coordination problems that option #5 involves (i.e. legislation). So even if someone feels option #5 is clearly best here, it may be worth supporting option #6 over option #2, say, while at the same time continuing to push for option #5. Again, I feel that in practice options #5 and #6 are more similar than many people seem to think.
Note that _all_ of these options except #1 can be (and have been), abused in various ways, unfortunately.
Do you see other options for financing post-secondary education? What options do you prefer out of the list above or whatever ones you add? Do you have fundamental disagreements with my characterization of the 6 options above?