Riding in the back of the pickup was the preferred method of transport when I was a kid.
I think in California, even your dog can’t ride in the back of the truck unless tethered.
That's because the system of roads was set up when people were free. When roads were made for cars, we were entering into an age where government wanted to control everything. So instead of locals being in charge of their local roads, and people coming up with non-governmental ways of developing a network of highways, the government stepped in, created the roads and then created a new system of governing everything that happened on them. The traffic cop was invented, the stop sign and light, the driver's license, and on and on.
Freedom of movement is severely proscribed compared to then. We can go wherever we want, and get there easily, and for that I am glad, but wherever we go, our movements are tracked, taxed, regulated and licensed. I think there is a less oppressive way to have set up our transportation system.