Dorm living is costly because the student has to pay rent and other living expenses. If the student decided to move home with the parents and commute money could get saved. There would be concentration on the books instead of worrying about how to eat and pay next month's rent.
No, it does not cost more to live in a dorm room or a first-year dorm room, because most students spend less when they live on campus than when they live in an apartment. Living in an apartment, a student will eat less, and they spend less on furnishings. In the end, it is better.