The entire notion of "Customs" searches seems unconstitutional to me. I am a US Citizen on US soil, and the government has no right to search me or my belongings unless they have reasonable cause to suspect that I have committed some sort of crime. The situation is even worse for private pilots who must sometimes land at airports they had no intention of visiting so some government lowlife can come and inspect their dirty underwear.
ML/NJ
Once you get inside the United States you might well have those rights. Until admitted you don't.
The way to avoid this problem is to NOT LEAVE the country.
BTW, this is not really a new policy.