This is not about crossing the border.
I know, I used to say the same thing to the guys 50 miles in when going through the highway checkpoint...they were also used to me.
I certainly do not look Mexican :-)
I doubt they caught many illegals that way since there were side roads that avoided the checkpoints.
What a boring job theirs must have been.
Here is a video I made in Juarez when they had the military on the street due to narco violence.
https://www.youtube.com/watch?v=AFNM4VM236E