Off-campus housing often looks cheaper, but that's because you're often comparing apples to oranges. As you mention, the age of the property and how well it's been maintained often varies significantly. But most places you rent off-campus don't include utilities. --That old house in the Midwest or Northeast might look cheap compared to on-campus housing in August, but your electricity and gas bills in the fall and winter will quickly change your calculations.
Another thing to keep in mind is that, on average, students living on campus have higher GPAs, are less likely to drop out, are more likely to finish on time, feel a greater sense of social belonging, and are more likely to participate in extracurricular activities. Those benefits need to be factored in as well. There have been a number of studies about this, here's a summary of one of them: https://studentlife.uoregon.edu/student-success-and-housing-....
When it comes to meal plans, if you have your own kitchen then yes, you definitely CAN eat cheaper, but I don't know many college students who actually spend much time planning their meals, buying in bulk, and actually cooking the majority of their meals from scratch. Realistically they end up eating a lot of frozen dinners and eating out - especially for lunch when they're on campus anyway. When I look at the school I went to, their unlimited meal plan ends up costing about $9/meal on average, which is a lot, but that's 3 hot meals a day, all you can eat, and you don't have to spend time buying the ingredients, cooking the food, and cleaning up after yourself.
