Caxsunray.
Correct, airports make very little money from landing fees.
As you say, the vast majority of profit is made from concessions within the terminal areas and that takes passengers, hundreds of 1000s of them and hundreds of 1000s of passengers each year is something that Carlisle Airport is not going to get under any circumstances.
Carlisle just doesn't have the customer base and the catchment area is well served by the likes of Newcastle and Glasgow for the most competetive/profitable passenger routes.
Money can be made from freight, but not enough to justify the proposed expansion of the airport.
Given that planning permission lasts between 3 and 5 years, I suspect that Stobart are going to use the planning permission approval to expand their road freight transport operations at Carlisle airport, but make none of the much lauded improvements to the airport itself.
Eventually, they would perfectly justified in saying that the airport expansion plan is after all, no longer viable, but they will continue to expand the road freight/industrial area into the existing airport infrastructure, thereby guaranteeing a major contribution to the local economy (which the airport itself never will).