Why do arguments against the "retentionist" cultural policies of source nations ring so false?

The answer is that those making them -- the heads of encyclopedic museums -- are so clearly arguing in bad faith. Their agenda is not to promote exchange of cultural materials: that could be accomplished through loan or touring exhibition agreements that preserved the source nation's ownership of the items. Rather, it is to make it easier for more antiquities to flow into the antiquities market and, via collectors or through direct purchase, into their museums' permanent collections.

Nor are they interested, really, in protecting archaeological objects, either in the ground or out of it. The claim made by Cuno, de Montebello, et. al. is that if they would relax their own anti-export laws, poor source countries could sell their "excess inventory" and raise the money needed to improve site protection and museum conservation. But money could be raised far more effectively by changing our own laws. A tax could be imposed on all sales -- and even on gifts -- of antiquities, with proceeds dedicated to anti-looting and conservation efforts in the countries of origin. Such a tax would be small change for the wealthy collectors who drive the market. A single Mesopotamian figurine sold last year for $58 million. Had it been taxed 3.5% this one sale would have provided enough money to cover the entire 2003 budget of Iraq's State Board of Antiquities and Heritage.