Given the density of the US rail network it's rather more than "last mile", but yes - rail depots are not where you actually want the goods to be in most cases, and you need to do something about that. The question is more whether it would be more efficient to only truck goods as far as the nearest rail freight node and then have it shipped that way rather than via interstate. The article here suggests that's not viable because many vendors are shipping quantities that aren't economically viable given rail freight costs, but doesn't really address why that's the case.