"Netflix on Apple TV asks me to select a user every time I launch it. I've had this account for 15+ years, and never had more than one user on it. I always select the only option there is to select. There is no setting to disable this screen."
Programmers :-D
This may be a case of a "speed bump" where they are giving an opportunity for the user to recognize/acknowledge the account that is signed into the device.
Sadly Dropout.tv just started doing this to me too (a user selection screen with only a single user on every app start).