Why are Dealers so Paper-shy?

In March, Egypt requested that the U.S. adopt new rules that would empower U.S. Customs officials to seize looted antiquities from that country, the subject of this week's hearing [...] At the hearing, antiquities experts faced off with coin dealers [...] Even before it began, the hearing attracted hundreds of public comments from both sides, most of them from coin collectors calling for an exemption from the proposed restrictions. [...] The committee asked coin and art dealers at the hearing what prevented them from better documenting their wares to prove they are legal, a sticking point often raised about the proposed import restrictions.

Dan Vergano, 'Archaeologists warn of a 'pillaged Egypt' in 25 years', National Geographic Channel, June 3rd 2014.