"It's the publishers" skips the part where you choose what your students will study, and how they will be graded.

Pearson cannot force a student buy anything. But you can.

The moment you decide your course will incorporate MyLab, McGraw-Hill Connect, Cengage MindTap, or WebAssign, the student is on the hook to buy the access code, by buying a brand-new copy of the book. The access code isn't a freebie that comes with the book. It's the main reason to buy the book.

That access code does one thing: it moves the grading work. Grading used to be your job or a TA's, and it was paid for out of the tuition fees the student already paid to your employer.

Now you're double dipping: you make the student pay tuition fees to attend your classes, and then you make the student pay your outsourced auto-grading provider.