What happens to the old retired airframes? I see a lot of reference made to them being placed in a desert somewhere. Would it not make more sense to cut them up, and melt the raw materials? Is it a cost thing?
Aircraft are normally only parked in the desert while their fate is being decided, which will in a minority of cases will be a subsequent return to service, but more usually eventual scrapping/recycling.
There are several dozen companies around the world who specialise in dismantling aircraft that have reached the end of their lives.
Here's an example:
Aircraft salvage, recovery and disposal services - Air Salvage International