They’ve also got smaller sizes (down to regular cars with a square trunk like the Kangoo which a locksmith might use).
Ain’t no way you can put even remotely as much in a pickup truck as you can in a Sprinter (or equivalent, there are a lot of companies in that game). By putting the bed much lower and having vertical walls as high as will legally fit in a standard tunnel, space is simply maximized in a way that a high bed with short walls cannot compete with, geometrically speaking. I’ve filled one of these bad boys with enough insulation for a whole house, and didn’t even have to bother with straps. If you’ve got gross shit to put down, that’s fine as well, the bed is built for it… Just hose it down at the end of the day lol, it’s no different than a pickup truck.
These vans are so spacious that they’re frequently converted into minibuses, it’s absolutely wild. Throw in a mattress, bedframe, wardrobe, couple of TVs, washing machine, dryer, and you’ve still got several m³ on top to stuff with boxes and bags and shit. Literally the only downside is that they won’t go up an 45° mud slope, which is why pickup trucks do exist in Europe, mostly in mountainous areas and occasionally on logging trails that get really muddy.