I believe the hanger steak is also known as the Butchers cut or steak. A lot of time the butcher would take it for themselves.
We've butchered a few cows and made sure we got them back. One we took right after the slaughter and the other was sent thru the cut/wrap process like a normal beef does. I can't believe what hanging meat does for 2-3 weeks to a steak, especially this one.
The one that wasn't aged was tough, chewing and lacking beef flavor. The one that was aged was completely opposite and now my second favorite steak behind a ribeye. We've ate a few off elk thru the years and there good but i would rather have a sirloin from an elk than the hanger.
I have heard them as butcher steaks also. If I remember correctly the Hanger Steak it the only muscle that there is only one. All other muscle groups have one on each side.