People seem to be assuming that TV companies hold 'in perpetuity' broadcasting rights to the movies in their vaults. I doubt that it's the case.
It's far more likely that a film distribution company will offer a movie to a TV company for (say) ten weeks for x thousand pounds, with the option to pay 20x thousand pounds if they want to buy the rights to show the movie indefinitely. As the majority of Freeview channels are operated on shoestring budgets (with many constantly close to bankruptcy) they simply can't afford the higher payments, so they only buy the broadcasting rights for a fairly short period. Once they've done so (and without the money to buy much else to fill their schedules), they're then more or less obliged to show the movie lots of times in order the get their money's worth from the deal.