I remember while living in San Diego, that Continental gave their reasoning for D/C that flight from SAN-MEX, as because the Mexican peso collapsed, and few rich Mexicans were flying up to San Diego to vacation anymore. I can't remember if they started again or not. San Diego is too close to TIJ, to have any real service to Mexican cities (outside of vacation resorts like Puerto VAllarta or Los Cabos). Most Mexicans skip San Diego for the anonymity of Los Angeles area. In the past, they've been made VERY aware that they're not welcome there.