Why do some eunuchs can't leave the palace, but some eunuchs buy houses outside the palace to live in?

The so-called eunuch can't leave the palace, in fact, it means that he can't leave the palace at will, just like he can't leave his post at work. However, leaving the palace is too common. There are too many things that need to be done in the palace, such as purchasing, and outsiders can only send them to the palace gate, while all women in the palace are absolutely forbidden to leave the palace for fear of having an affair with the outside. All the things that the harem empress and princess want personally must be purchased by the eunuch, as well as delivering orders and goods. In fact, if you think about it carefully, life in the palace is so particular about food, clothing and use, which is much better than that of ordinary people. It is natural to have contact with the outside of the palace, and the eunuch is the most convenient to walk around inside and outside the palace, so the eunuch can't leave the palace, but he just has to follow the rules when he leaves the palace. Every day, eunuchs run back and forth inside and outside the palace. In many film and television dramas, emperors, princes and princesses want to sneak out of the palace and dress up as little eunuchs, which is also the reason.