You're trying to argue that forcing the entire population to pay for college education for everyone is justifiable even when the people going to college may study subjects or intend to enter fields that have very poor financial prospects or lack productive value for the society as a whole.
As opposed to....
A system in which people have the freedom to decide for themselves how to allocate their own financial resources based on their career goals and not use other people's money to fund 4 years of useless study (if they study a useless subject)?
You have a very skewed understanding of what is fair and justifiable.
If people make poor financial and educational decisions, that's on them. Don't punish the rest of society by forcing it to foot the bill for someone else's foolishness.
The sad thing is, Europeans will be the indentured servants for the rest of their lives because of the depressed wages they'll have to endure and the high taxes they'll have to pay.
The fantasy that the US system is someone leveraging market forces to optimize efficiency is ludicrous. 18-year-old kids have no idea of the impact of 5 or 6 figure loans at various interest rates and their expected ROI. Even many of their parents, who had good post-war working class union jobs with a nice pension and affordable homes they could buy in their early 20s have a blind spot around this because all they know is that the career paths they enjoyed are dead and gone and just some vague ideal that "college-educated" is still a meaningful adjective.
Frankly, it's an embarrassment to even try to sell the idea that the US system is better. The only significant difference in outcomes is that a huge portion of young Americans are destroying their lives with unmanageable debt, where EU citizens may get an inflated degree but they won't be an indentured servant for the rest of their lives.