Forget about NAFTA. Fox is just playing catch up. If an American citizen, traceable and with property, does recreational drugs, he risks having a lot of property seized, simply because he's an easy target. If an illegal alien does illegal drugs, no one cares. Why should a Mexican have more rights in the U. S. than in Mexico? Fox is just leveling the field for his citizens.
Come to think about it, why should an illegal alien have more rights (or at least be less subject to the law) than an American citizen?
You have nailed it. It's about the money. The authorities can seize assets from a U.S. offender for minor offenses, but there is nothing to be gained from an illegal. I think that the seizure of assets for minor crimes needs to be severely restricted, and officers should have their priorities directed instead to more serious crimes. Too much money, manpower, and resources is devoted to petty nonsense.