Anyone buying used delivery trucks knows they get driven all day every day until it's uneconomical for the owner to continue operating them. Hundreds of thousands of miles. It would be very unusual to see one for sale with under 200k miles, that's "just getting broken in" for trucks like this.
I'm even surprised that these trucks have mechanical odometers. I havent's seen one in a passenger car in many years, they are all digital, rarely fail and (I assume) would be harder to tamper with.