traveling into mexico you get a red or green light - its completely random. if you get red, you get inspected.Last time I drove to Mexico (which was a long time ago 13 years ago). They let anyone drive across with no border check. Is it different now? I think it's a great idea to have people do backyard flocks there. It is a great source of income and nutrition to a family. And there is always a market for eggs.
the same applies to flying in but you get to press the button that decides.
my counts are less than 1:10 chance of being checked.
I have crossed at TJ atleast 20 times and have never been inspected at border by Mexican customs