An MSNBC reporter recently received a real world lesson in why President Trump’s promised border wall is crucially important to stop illegal immigration along the U.S.-Mexico border. A reporter covering prototypes of Trump’s proposed border wall taking shape near San Diego, when the interview was interrupted by a group of “migrants” hoping over the existing fence. “What happened?” the reporter shouted as a group of agents on horseback move in to nab the border jumpers. “The people are crossing!” “Almost on cue, a group of asylum-seekers, migrants not from Mexico, jumped over the existing fence to turn themselves in to...