While reading a New York Times article, I read the line in the title and pondered on it. Indeed the history of Latin America is full of coups by their military forces, to the point it has assumed cultural meme status in media so much that there is a tvtropes page dedicated to its pervasiveness in media.

While Mexico has experienced civil wars, revolutions, monarchies, and rigged democracy, it's never had a military dictatorship like almost every other Latin American country in the usual sense. I know Porfirio Diaz in the late 19th Century rose as a military general through a revolution and maintained power through rigged elections, but his leadership and marginalization of the military is not quite the same as Pinochet as an example, making him a dictator of course, but not a military dictator in the sense of a Manuel Noriega. Additionally, since the 1920's Mexico has not experienced any coups of any definition at all, unlike other nations.

Yes, it is a quibble of semantics of what qualifies as a "coup" and a dictatorship, admittedly.

So what has made Mexico relatively free of dictatorships to substantiate that statement?