Why do bathrooms have locks on the inside if there is already one on the outside?

 Bathroom doors typically feature locks on both the inside and outside to serve different purposes. The lock on the inside is designed to provide privacy and control to the person using the bathroom. This interior lock allows them to secure the door from the inside, ensuring that they can have the privacy they need without the risk of someone unintentionally walking in on them.

On the other hand, the lock on the outside of the bathroom door serves a different function. It enables others in the household or public setting to secure the bathroom when it's not in use. This exterior lock is particularly important in shared spaces to prevent accidental intrusion and maintain a level of security and control over access to the bathroom. 

Having both locks contributes to the overall functionality and versatility of the bathroom door. It accommodates the needs of both those inside the bathroom, who require privacy, and those outside, who want to ensure the bathroom is vacant before entering. This dual-lock system is a practical solution to address the diverse requirements of different individuals using the same space.