A looot of universities use online homework tools from the big textbook publishers especially for first year classes. Each new book has a code the students can

A looot of universities use online homework tools from the big textbook publishers especially for first year classes. Each new book has a code the students can use to access the homework included. Buy a used book and you now need $80 or whatever code often making it more than the new book. Worst part is there is open source tools that are similar but take effort to setup and host so universities don't use them.