Things in the school supermarket are generally a little more expensive than those outside. Especially those who make money are generally opened by relatives of school leaders. If anyone wants to drive, it will be easy to earn millions a year.
All kinds of service industries around the school are very profitable, not to mention the golden position of the school.
Students don't care that there is only one supermarket in the school that raises prices. If there is competition between several supermarkets, it is a supermarket.