Hmm
I have just read on the FAA site and it doesnt say that. It seems to say:
(b) Certificate issued. A U.S. private pilot certificate that is issued under this section shall specify the person's foreign license number and country of issuance. A person who holds a current foreign pilot license issued by a contracting State to the Convention on International Civil Aviation may be issued a private pilot certificate based on the foreign pilot license :without any further showing of proficiency
Now I am confused.