Some fun pickup truck fact's...
Prior to WW ll Ford, Chevy, Dodge pickups and trucks were produced all over Europe, Asia, China, Philippines under license to the companies. WW ll saw axis powers take over the factories. When you see a WW ll movie where it looks like the Germans or Japanese are driving American trucks, they are as they used the factories for themselves along with all the tooling.
After the war, the reason European and Japanese trucks got so small was simply due to a shortage of materials, shortage of gas, and cost. If you look at the Matador and the Gutbrod you'll see the frames are nothing but tubing and the bodies are simple flat steel stamping's, due to lack of machines at the time. Steel was saved by making the beds from wood.
In Europe the reason for small and very small engines was because at the time, after the war, people's vehicles were taxed by their cc displacement. Thus you will not see many engines over 999 cc as that was a big increase in tax's 1000 and up. Only the rich and well to do could afford regular cars and trucks. The smaller the engine the smaller the tax.
Also, in Europe and Japan, there is not much oil produced and almost all fuel had to be imported raising prices. Small engines use less fuel.
You may also see some 3 wheeled vehicles called "trucks". These were made by companies that had specialized in motorcycles and bicycles. They also didn't require any big costly machinery to produce.
They were also taxed as "motorcycles" and had small cc engines, thus tax was minimal.
Britain made small cars for their fuel efficiency, and also because getting around their post war cities was hard due to very narrow streets and roads of the time. Also, $$$. Only the well to do could afford large vehicles and the gas to power them.
Just some history for today...