> To me, this mostly sounds like Apple taking US laws too literal/general.

Unfortunately not. The relevant definition of "export" is the one at Export Administration Regulations § 734.2(b)(2)(ii):

  (2) Export of technology or software. ...:
    (i)  Any release of technology or software subject to the EAR in a foreign
         country; or
    (ii) Any release of technology or source code subject to the EAR to a foreign
         national. Such release is deemed to be an export to the home country or
         countries of the foreign national. This deemed export rule does not apply to
         persons lawfully admitted for permanent residence in the United States and
         does not apply to persons who are protected individuals under the Immigration
         and Naturalization Act (8 U.S.C. 1324b(a)(3)). Note that the release of any
         item to any party with knowledge a violation is about to occur is prohibited
         by §736.2(b)(10) of the EAR. [0]

Apple's interpretation is the one almost all export-control lawyers will give their clients and is the one the Bureau of Industry and Security will give you if you ask for clarification.

EDIT: By the way, the reason Apple won't/can't sell iPads to foreigners in the US but can sell them the same product abroad likely comes down to paperwork. I am not Apple's lawyer, but I imagine Apple exports iPads under a provision of the export-control regulations that allows export of (a great many) controlled products without needing to obtain a license so long as the use of the regulatory licensing exception is properly noted on the export documentation. But Apple's retail stores presumably are not equipped to fill out and submit those documents, so they simply won't/can't sell to foreigners.

0. http://www.bis.doc.gov/policiesandregulations/ear/734.pdf [PDF]