I agree that ComUtoR is correct but that is the baggage that comes with the politicians promise of 'competition and choice'.
You have specificallly called out GTR, (I assume that the two 'GTM's were typos) but the GTR deal was a Management Contract and quite different to the Franchises that are now under scrutiny. The Southern/Thameslink/Great Northern/Gatwick Express deal was set up in a time when there were many risk factors that might not result in a competitive bidding process, e.g.:
The Thameslink programme was in full swing with numerous civil works, - the complete rebuilding of London Bridge, the segregation of the approaches from Waterloo East/Blackfriars/Cannon St, a grade separated segregation of the SE approaches with the Bermondsey diveunder, the extension of and various platform lengthening sites north of the core.
The testing, training for and launching in service of over 1000 new EMU cars onto one of the busiest commuter corridors in the South-East.
The complete resignalling of the core with ETCS to enable up to 24/30 trains per hour including all installation work through the Canal Tunnels to connect with the GN lines.
The launching of a completely new timetable affecting all four brands in the GTR network.
All four of the above groups of activity had a major involvement from Network Rail, which inevitably GTR took the hit for as par as the average traveller was concerned. Arguably, GTR did make a ham-fisted job of their part in the new timetable, especially in not admitting their shortage of route-trained drivers, but even there, Network Rail were involved as the issuing of timetables were delayed.
Had tenders for a normal franchise been invited, there would have been so many exclusions of or dependencies on NR activities that the franchise would have been unworkable. The management contract was a mechanism to pay GTR to run the service with a commercially viable profit whtever the impact of the risks were, that being carried mainly by the DfT.