As a CATV instsller, I can relate..
First, when the housing units were roughed in, all the comm. lines were brought out to power and cut around 2' from the wall.
Second, these units are owned either by a private renting company or are condos managed by a home owners assc. They probly didn't want wires going upward to the roof. I.E. cosmetics
Third, one of the dish companys either offered to install thier equipment for free to make selling the tenants easier, or the cable wasn't accseible yet, again making the dish salesmans job easier.
Finally, In all actuality, thier are lots of variables, coming down to the final inspection being before the dish installations. I think that there might be some sort of high voltage lines or some other obstical limiting the placement of the dishes. I worked for Directv when Primestar went out of buisness doing the switch outs. The satellites were in diffrent locations in the sky, but we tryed to use the existing mounts. I went as far as cutting down an offending tree for one of my rural customers.
