You miss the point. I'm not saying anything about Mexicans that doesn't apply equally to Americans, or anyone else for that matter. Being warm and friendly doesn't get the job done.
In order to restrain evil, you must restrain yourself. Who do you think is offering the bribe money? The warm and friendly participate in that corruption because their self restraint is not strong enough to resist it. It is easier to be pragmatic than to resist.
There is some truth is what you say, but could you do better, if you had no history, no background, no experience with living under true freedom?
I doubt if i could.