Illegal Immigration Via Plane

I just returned from a 2.5 week trip to Mexico. Such a lovely country…A random thought on immigration…it’s really a “I just don’t get it question”. Here it goes: If so many Mexican citizens are willing to risk their lives crossing over the border into the USA by foot or in the backs of trucks or by other dangerous measures, while foreign visitors to the USA with a passport can simply board a plane to the US and enter our country and visit for 2 weeks or whatever the limit on days is for a visit / vacation and then fly back to their respective home countries, then Why Don’t Mexicans just get a passport and a $250 ticket to Los Angeles, fly to the USA, walk through customs as visitors, and then never go back?  It can’t be because the $250 is tough for them to come up with because with the way I saw money and cash and goods and services being exchanged in Mexico, most folks should be able to save up $250 in no time.  So what’s the reason? For judgmental folks out there, I am totally not advocating illegal immigration, I just don’t understand why immigration via plane isn’t a popular method or a popular target of the media.