Can someone explain to me the thought process of an engine cutting off when you stop at an intersection , etc

Buddy of mine has new company truck (Chevy ) and we went to lunch one day and every time we stopped the motor cuts off , he did tell me there was some sort of override he thought (Company truck so he drives what ever they put him in ) Over all very nice truck though


Far from a mechanic’s standpoint what is the point in this, I know I am old but was always told starting a vehicle was harder on it than leaving it running

I know lot of vehicles have this option now days

Like to hear a true mechanic’s thought on this process