You'd be wrong.

There is an enormous and growing market in Mexico for anything will pop a 5.56. 7.63x39, 7.62x25, 9mm, or 45 ACP cap. Burglaries, straw purchases, individual private sales, questionable gunshow sales are all used, usually by fine folks who smuggle dope and people north, then guns, ammo, and money south. It's worse today than even the 90s because jobs here are plentiful, licensed marijuana is legal and hard to distinguish from illegal weed, the fentanyl market just keeps growing, and the US checks exactly NOTHING southbound into Mexico.