My best guess is that they have learned that going non standard and making things work always comes back to bite them.
They put in the 3LNB since the customer says I don't need the stuff I'll lose. Then a little later the customer call D* and says why can't I get ......
I've found out through life experience that anytime you go non standard or go that long extra mile that a customer wants they either go cheap on you or complain, complain, complain after following you around slowing things down since they want explanations of everything being done.
Where I am now We require a deposit on computer repairs. I've got three sitting on the shelf now where I took them against my better judgement when they claimed not to have the deposit. They'll still be sitting there in 6 months.
Call DirecTV and tell them their cheapness by going to flat rate installs is killing your install. Don't blame the installer for not wanting to spend a whole day on something that will most likely become a charge back and net them 0$.
Blame DirecTV for the system they chose. Then if you still want their product find a local installer and pay the price to have it done like you want.
I have a customer who insisted I use a mast location very close to a tree instead of the clear shot that could be seen from the street. As the tree grew she started calling to get me to move the dish.
Relocate dish = $100.00. I don't even answer the phone. She calls every time it rains.