Prenuptial Agreements

This website has information on the Halakhic Prenuptial Agreement.

However, in a letter printed in the current issue of The Jewish Week, Susan Aranoff of Agunah International argues that the prenuptial agreement does not work (link):

Several agunot have told Agunah International, “My pre-nup wasn’t worth the paper it was written on.” One agunah capitulated to financial extortion after being told by a civil court that the RCA pre-nup was unenforceable. Questions have also arisen about the effectiveness of the RCA pre-nup in California. In a second case, the recalcitrant husband withheld the get for over a year despite having signed a pre-nup. In a third case the husband, who already had a new girlfriend, withheld the get until the agunah submitted to the settlement that he dictated.

None of these agunot received a penny of the $150 daily payment due them as a consequence of the husband withholding the get. The recalcitrant husbands got off scot-free despite having extorted concessions and tormenting their wives.

Granted, Aranoff makes it clear that she advocates R. Emanuel Rackman's method of "freeing" Agunahs (that R. Chaim Jachter critiques in detail in his Gray Matter volume 1). But, setting that aside, is she correct that prenups don't work?