> I don't really see the point of them.
Then you need to get our and do more real work of lots of different types. Exposed bed is often an advantage!
I have a welder, the safety instructions include "Never carry the gas tanks in an enclosed vehicle" -if there is a leak the gas tanks (nitrogen, argon, helium) can quickly displace the oxygen inside and I'll die before I know what happened.
Most things I carry don't need to be inside constantly. A little rain won't hurt anything, I wouldn't want to store anything outside but just a couple hours won't harm most things.
Also it is a lot easier to load things in a truck than a van. I can lift it over the sides (perhaps with a forklift). I can stand up in the back while arranging things - even when it is full I can stand upright.
I have used both trucks and vans to carry things over the years. Both are a compromise - and like all compromises there are negatives where something else would be better. Overall I fall on the truck is better side for what I do most often - but that is overall and I recognize there are good reasons some will choose something else.
Every Saturday I fill my truck bed with garbage cans and dump them at a transfer station across the highway from where I live. (We have no trash service in this rural area). I used to cram bags of trash into the back of my Honda CRV, which worked, but was often messy and stinky. You can hose out the back of a truck bed.
I used to think trucks were mostly useless, but have found that many people have weekly uses that make a lot of sense.
I do question the logic of lifting your truck so high you can't reach into the bed.
A dropside van is usually used for that kind of task in Europe: https://www.autotrader.co.uk/vans/used-vans/dropside
Lifting things in and out is considerably easier when you don't have to lift it over the sides.
> if there is a leak the gas tanks (nitrogen, argon, helium) can quickly displace the oxygen inside and I'll die before I know what happened.
This is something so many people don't realize.
When you hold your breath for too long, that feeling of suffocation isn't caused by a lack of oxygen, but the build-up of CO2.
If you replace the oxygen in a room with an odorless gas non-oxygen gas, your body doesn't tell you. You don't feel like you're suffocating. You just start suffering the effects of lack of oxygen. Dizziness, confusion, lightheadedness, but you likely won't realize anything is wrong. Your judgement and ability to react goes away and you lose consciousness without ever experiencing the desperate urge to breathe.
Another good example of this is when pilots fly too high without supplemental oxygen or adequate cabin pressurization and become hypoxic. They become confused and lose coordination while feeling perfectly fine. By the time they realize something is wrong, they may no longer be able to do anything about it.