Is there a reason that you can't respond like a mature adult?

Are you really thinking this through, or are you just trying to be obnoxious? We are talking about clearing immigration and customs here. American airports are simply not designed this way, nor should they be. How would you possibly do this? It would require that every single airport terminal in the country have immigration and customs facilities. Every single person who gets off a domestic flight would have to checked to see whether he/she had cleared immigration previously or not. Yeah, THAT sounds like a great idea!