SAN typically uses the BARET4 arrival STAR for flights from the northeast, which begins at Needles, well to the north of the Mex border where Calif, Nev, and Ariz meet. Also would mean leaving SoCal Approach airspace if the plane ventured into Mexico.

ELP-SAN usually rides J2 over Interstate 8, so even that flight stays north of the border.

Might happen from time to time, but for whatever reason, US airlines don't fly over Mex like they do Canada on northern routes.