The problem from a broader point of view is a coordination problem. The people making the buying decisions (professors and departments) are not the people paying (the students). I would wholeheartedly support legislation that forced professors to pay the same textbook fees as their students, and for departments to be required to cover the costs for scholarship students.
I’ll bet we would see a lot more schools opting into open source textbooks and articles from the library if that were the case.
What will happen is that universities will pass these costs to all students where now paying students will pay more.
A better regulation will be encouraging and funding more open access materials that can be used and require public funding receivers to adopt them or decrease the funding and cap the tuition increases.
This is how we are. For now.