Depends on if he's self employed or not. The one we had when I managed the mattress store kept one with him for his reciept book and other receipts he acquired while making his rounds.
I probably wouldn't have said Anything except I had a clueless person ask me why the hell I needed a briefcase when I was driving cab. You wouldn't believe the amount of paperwork involved in that job. My daughter has it worse because she's a truck driver.
You never know why someone buys anything. I bought 10 bottles of balsimic vineger this month because I got a smoking deal on it. 49¢ a bottle, marked down from $4.99 I won't use it all right away, but it'll get used.