It may surprise some but lard is used all the time when cooking authentic Mexican recipes. Butter is used in the Mexico a lot, but as Mexican cuisine author Maya Pillai plainly explains, if you're eating butter, you aren't eating authentic Mexican:
Though today people use refined vegetable oil as fat for cooking, the ancient Mexicans used lard. Butter is never used in a traditional Mexican cuisine. Lard adds aroma and favor to the masa used for making tamales.
Read her interesting article about some of the history of Mexican cuisine.