You're trying to start in macOS Recovery and are asked to choose a user and enter a password. Why is this required?

When you are prompted to choose a user and enter a password while starting in macOS Recovery, it indicates that FileVault is enabled. FileVault is a built-in disk encryption feature of macOS that protects your data by encrypting the entire startup disk. When FileVault is activated, the system requires authentication from an authorized user to access the encrypted disk, even in Recovery mode. This security measure ensures that unauthorized users cannot gain access to sensitive data, as they would need the valid credentials of an authorized user to unlock the disk and perform recovery operations.

The requirement for a username and password in this scenario directly emphasizes the importance of protecting user data and ensuring that only those with proper authorization can make changes, particularly in a recovery environment where critical tasks can be performed. Therefore, the necessity for user authentication in this context is a direct consequence of having FileVault enabled on the device.