The reason why the door can't be closed should be to make it easier to check the dormitory, but also to prevent students from quietly hiding contraband when checking other dormitories, so that things that shouldn't be in the dormitory can be hidden. The reason why there can't be anything on the table, I think, is to make the dormitory look neat.
Trash can't contain garbage, but it should convey an idea: as a college student, we should always ensure that our garbage has a place to put it, and the garbage suddenly produced has a place to put it, so that the dormitory doesn't look messy. At the same time, if there is garbage in the trash can, it may give off some smells that are not easy to eliminate after a long time, which will have long-term harm to the dormitory, so it makes sense that there is no garbage in the trash can.
No one should make people feel better in bed, and at the same time speed up sleep check. Imagine that people from the dormitory are coming and everyone is lying in bed. No matter how to check, it is not appropriate. So there are four unsolved mysteries in the legend, which can't be said to be unsolved mysteries, because since there is this rule, there must be a reason, so there must be a reason for the strange rule, so let's implement it.