Because they do sell the giblets by them selfs too. You can buy a package of, say, hearts or liver. Also, you can buy turkey parts too, turkey breast, drums, etc.
Also, when they are cleaning the turkey, its now like one person opens it up, takes out ALL the insides, cleans the cavity, separates the good parts from the bad parts, and then put the good parts inside the turkey. Instead is a process done on an assembly
line by several people and machines. So when they open it up, all the insides go together, and in a different process from what ever that turkey is going to be, either parts or complete, someone separates the good parts from the bad ones, clean them up and
they end up all together. They bag then and THEN they go back into the turkey.
Excuse me now while I go make myself a turkey sandwich.