Technology

Even then they shouldn't be allowed imho, a van is a much more practical work vehicle and is actually designed to be practical for work. A van sits 2 or maybe 3, not sacrificing a huge amount of space for backseats and an extra set of doors. There is usually one or two big sliding doors, which don't require a lot of room to open but provide a lot of access. They don't have a huge nose with a giant engine. The nose is kept as small as possible, so the space is maximized whilst the vehicle size is minimized. The driver position is designed to have maximum visibility, the vehicle is expected to navigate relatively small spaces, with other people also working there, so you need to see as much as possible. Two big doors in the back give plenty of access and usually can be closed in a way larger cargo can stick out of the back (within safety limits). Usually there's also a roof rack, with some trades permanently mounting stuff like ladders and conduit. Large long items can be securely transported there. All other cargo is inside, not exposed to the elements or theft. The metal panels are kept flat, this again maximizes space whilst minimizing vehicle size. The panels are also very easy and quick to repair, as damage is expected being a work vehicle. The places with the most chance of damage usually have blank metal bars, when damaged they can be repaired or replaced easily and cheap. Vans overall are way more practical, cheaper to own and operate and actually designed with a working life in mind.

The whole big trucks are for work argument doesn't fly, they are super impractical for actual work. Maybe a pickup truck from the late 80s or 90s filled the role as a mix between work vehicle and daily driver better. Which could be useful for rural people which wouldn't have to have multiple vehicles. But not today.