If I had to guess, this avoids the classic case of staring at someone a little too long to read their shirt. The shirt design isn’t so much for the wearer, it’s a billboard to others. Also, printing on the front has much more noticeable texture than printing on the back which would make the surface a bit uncomfortable across the entire front as opposed to the back where you’ll hardly notice the feel.

Even the best screen printing techniques have at least a bit of feel to them.