It comes from earlier humanized thinking about shirts, because generally speaking, the use of shirts in the early days was mostly used by intellectuals, representing their identity. Many official jobs led these upper-class people to choose places where they changed their clothes in every venue, such as bathrooms, and sometimes the dressing rooms were not necessarily available.

In a slightly advanced hotel bathroom, there will be hooks in the toilet, which is why we can see hooks in a slightly better public toilet now;

These things have been inherited to form a clothing standard, and the buttons at the back are habits, which are made for the convenience of users to hang clothes.

In fact, in clothes that are not shirts, there are usually such things. Most of them have a buckle belt under the neck with a trademark printed on it, which can not only facilitate users but also play an anti-counterfeiting role.