Why do travel agencies require us to bring slippers when traveling in Britain?

Because British hotels generally do not provide slippers, high-end brand hotels may provide indoor slippers (generally not based on experience). If you are not used to drying your feet with a mat before you step out of the bathroom, you may slip because of the water stains you brought out of the bathroom, and even receive extra cleaning fees from the hotel because of too many water stains in the bathroom. Most people in China are not used to not wearing slippers in hotels. For example, my parents always bring their own slippers when traveling abroad, and the tour guide kindly reminds them.