XC can only use what the DFT gives them, and due to supply and demand, if you don't have enough supply for the demand, then a solution is to suppress demand with high prices. It also makes business sense to make as much money as possible. TPE on the other hand is just a lost cause.I might want to remove Avanti from FirstGroup too, indeed I do, though it has pulled back from the brink a bit. However north WCML express services should be one TOC.
XC on the other hand, you think they and their nasty, overcrowded Voyagers and excessively high fares are a good TOC to bring in? In 2019 I'd have said they were one of the worst.
And why has Avanti been given priority over XC and TPE? Because it serves London. I don't like it myself, but apparently funneling everyone into a single mega city is important to those in power, even if it turns the place into a horrible place to live.