Most Mexicans do not use lettuce on a true Mexican Taco.
Unlike Americans who use mostly lettuce a Mexican usually puts fresh cilantro leaves on their taco in place of the lettuce that most Americans put on Tacos.
A true Mexican Taco contains no lettuce but instead uses the fresh cilantro leaves as well as finely diced onions and shredded cheese and tomatoes.
However some Mexicans may prefer lettuce on their tacos which is okay as well but True Mexican Tacos are made without lettuce.
Also Mexican Tacos are made with soft corn tortillas as the wrapper while American Tacos come in both kinds which is soft and hard.
Mexican Tacos are always the soft kind of Tacos.