> The problem with rail is that most businesses don't want a whole train worth, and removing just a single car from the train is hard.

You don't need to remove cars from trains. The transportation world has been moving around shipping containers for almost a century. Shipping containers, also known as intermodal containers, were designed specifically to simplify the task of moving arbitrary units of cargo between modes of transportation, which includes to/from trains. You just need to drop them off on a flat car, take them from A to B, and then drop them off to handle the last mile.

Why don't containers already solve that problem? You can unload individual containers just fine, even put them on a truck for last-mile delivery. And then there's this American idea of putting entire trailers on flatbed cars, so you can just roll them on and off.