I'm going to wager this was implemented to keep drivers from talking on the phone all day and because it's using machine vision it doesn't know the difference.
Exactly what I was thinking. I wish I was an extrovert. I enjoy the occasional phone call but mostly I just wish I could hang up, even with friends.
My main USPS worker talks on the phone at all times. I see her every weekend and she is NEVER not excitedly or angrily talking on her earbuds. I bet it makes work a lot better for her but holy shit who can just talk on the phone literally all day long.