The issue might go a bit deeper than that though, and I think it’s worth thinking about it:
It is definitely not hard making a very simple cart out of wood and nails, given the right tools. The Wheels might be bumpy because you won’t get them perfectly round, but I think most, if not all people know how wheels and an axle work. The axle might not be >steerable<, making the whole system a bit of awkward when turning somewhat tight corners, but I’m certain that every one of us could build something resembling a small, dragable cart.
I mean, It’s basically 4 wheels, stuck to 2 pieces of wood, a wooden plattform and some additional wood to make some U-shaped pieces of wood, to keep the axle in place while still being able to turn. That’s no real science, to be honest.
Is there an easy way to decrease the need for mechanics for certain parts/very small builds, because what you’re actually doing is so basic?
Or how about a crafting recipe, which produces a small, basic, handmade cart?