That's really annoying! But is there anyway to track which individual person did this? I remember they usually just put a generic official notice in the luggage for this kind of check.
I heard for passengers disliked by custom officers, they would put these passengers on a "black list". One on the list would be thoroughly checked every time passing an airport custom - I don't know if this is just urban legend.
As for mailed packages, there are people I know who had their moon cakes (the dessert for moon festival, which MUST be perfectly in a beeng shape for the celebration) mailed from Asia to US, or even within US, and then the packages were open and the cakes were broken into pieces for custom officers to search inside.