To be fair, in this case, he is indeed the back. The main lines in Tokyo tend to have them in the back, such as the Yamanote line, picture here. However, I agree with and have seen them in the front as well.
I think on the Sotesu line they drive the train from the front going to Yokohama, and from the back going to Ebina. Though I usually rode in the middle of the train as that was closest to the Sagamino gates, so I could be wrong about that.
I think Tsukuba Express is driven from the front both ways, between Tsukuba and Akiba. But it has been such along time now.