I'm not talking about high speed trains. I'm talking about medium speed cargo trains. Despite the lack of a flush body, each container does draft the following

I'm not talking about high speed trains. I'm talking about medium speed cargo trains. Despite the lack of a flush body, each container does draft the following one, greatly decreasing drag. Each car in a normal cargo train doesn't have its own engine. They are pulled by locomotives. This is more efficient than putting an engine in every car. Passenger trains typically do have engines in every car, but we're not talking about passenger train here.