> Why are student loans not tied to the value of the program, which determines their ability to pay?

They used to be because they could be discharged through bankruptcy.

Once you prevent people from being able to discharge the loan through bankruptcy, this is what you get.

How would humanities, arts, pure reasearch and the like survive in this model?

They might not. You have the degree program, and you have the classes. This sounds a lot like unbundling your cable channels. Maybe go for market prices per class. Some classes would be worth more than their averaged share of tuition today, others less. You could always turn class sign-up into an auction.

Reduce the tuition, which last I checked is still a substantial portion of the total cost of education.

How can a school charge the same amount of tuition, per unit, for different fields that pay substantially, sometimes orders of magnitude, different over the lifetime.

For example: MBAs, JDs, Medical fields' tuition is much higher. Why is that not the case across the board?

Would this then force companies to pay according to what universities charge? How are those levels determined?

Those are determined by demand and supply. Why does a society want to produce experts in fields where there is no value.

Note, many/most people in software engineering have other interests. But they have not made a career out if it. So, if humanities interests someone, it can be a perfectly good hobby for many, till demand and supply evens up that leads to rise in salaries.

“value” is ambiguous. Prices are set via supply and demand. In this case we see that students gravitate to certain manors more than others, and may not take into account future job demand. Many students may be following a lottery ticket model of buying the best education simply for a chance to participate in a particular job market.

If student preferences were different we could easily be bemoaning low value engineering majors, doctors or lawyers.

If student preferences are disconnected from long term utility then it's unlikely for University costs to normalize on utility. Increasing the costs for high utility majors would result in yet higher prices for those with the majors skills - decreasing prices for low utility majors will simply lower income potential in those majors.

Do they deserve to survive? Maybe state could subsidise certain number of positions. And distribute them by something fair like SAT score or proper objectively measured entrance exams.