What is the purpose of the lock phone when driving setting

[Android Central Question]

Android auto with Samsung s9

 

[B. Diddy]

Welcome to Android Central! When the phone is connected to your car system via USB and Android Auto is on, this option prevents you from being able to unlock the phone and using it separately from Android Auto (which presents a potential driving hazard). You'd then have to exit Android Auto or disconnect the phone from the car in order to access the phone.