They're also optimized for having a driver hand-deliver packages from the back of it hundreds of times over an 8hr shift. That's moving entirely different things than you'd move in a truck. A pickup truck would make a shitty parcel delivery truck, and a UPS truck would be a shitty way to move construction materials.
Amusingly enough a "step van" - the technical name for the type of thing a UPS truck - is often a much better truck for the average construction worker (the type who brings a truckload of tools to a job site) - as you can get into the truck and find things without having to unload the entire pickup.
A friend started construction and bought a Tacoma new because he saw everyone else using one - and it had to go in for a repair and during that time the dealer lent him a van, and at that point he had serious regrets about buying the truck.
But then again visit most construction sites and you'll see one or two company trucks full of tools, a delivery semi or two, and acres of pickup trucks with nothing in the bed.
I'm in a neighborhood with a ton of construction and remodeling. Here step vans, sprinters, and the like are very clearly much more popular with construction workers. Much easier to keep tools organized and securely locked and even more capacity than a truck bed.
What I have see is construction workers where the step van is the "work vehicle" and a crew cab pickup is the "family car" - though as often it's an SUV or a minivan.
Oh totally, that's why sprinter vans or step vans work well for tools and small goods. But if you're moving sheet goods, pallets/slats of heavy goods, long materials, or things like dirt or gravel, then a truck bed is better.
It's all about using the most suitable vehicle for the job.
