What makes you think that? If anything people with a CS degree can afford to pay more because they are in high demand on the job market.
Usually the rhetoric is the opposite. Economic STEM degrees will be very cheap or have low interest rates while some of the uneconomic liberal arts will have higher interest rates. Meaning only rich people will be able to get financing for the liberal arts degree. From a societal standpoint this is the correct course of action.
If people can support themselves then they have every right to get a degree. If they can support themselves through a job they deserve the degree. If they can support themselves by being rich they deserve the degree.
The only people who want a CS degree are people who don't have jobs in CS and who don't have a degree. Your talking as if the people without these degrees are already super rich.
A poetry degree should not cost nearly what it does.
CS education tied to ISAs makes education more accessible, not less.
The current system harms the poor.
As it is degrees are already tied to supply and demand economics, the supply is just constrained by admissions (often this is true of specific departments too).
This is good. If degrees were priced based off of supply and demand economics then only rich people would be able to afford a CS degree.
Currently the bar for getting a degree is partly economics and partly intelligence. You can't get rid of economics completely but at the very least they keep prices egalitarian and allow for raw intelligence to be a huge factor in acceptance.