This is easy to understand, but what is the status of would-be Mexican illegals?
The Mexican illegals have less rights regarding asylum than the other countries in central America. There is a loop hole of sorts that has allowed people from all the other countries (except Mexico)to get special waivers. I do not know the details, but this is why the problems are all the other non-Mexican countries.
We have a special treaty with Mexico and Canada.
If the Mexicans are not seeking asylum, they can be almost immediately returned to Mexico, without a judicial process.
But - we have to catch them first.