Sometimes Protestant missionaries are simply ministering to needs that are not being met. There is a shortage of priests in Latin American countries, that is no secret, and sometimes people have less contact with institutional Catholicism than is assumed.
However, sometimes the problem is that the Church actively excludes the perspectives of certain groups, such as gays and women. I encountered a Mexican Episcopalian priest some time ago that was a gay man. He appreciated the church because he perceived the Catholic Church as problematic for people like himself, in Mexico.
Likewise, Protestantism sometimes presents opportunities for Latin American women in ordained ministry: I watched a video on fundamentalism in Brazil by a Brazilian pastor (Rev. Dr. Wanda Deifelt) who was a woman. She was criticizing Protestant fundamentalism sweeping Brazil. In the Catholic Church, there just aren't the kinds of opportunities for women like that to be religious authorities.
In addition, Protestant Christians like Dr. Deifelt are Latin American, but they have a background that is other than Roman Catholic because their ancestors came from countries like Germany, not Spain or Portugal. Latin American is not just Spanish or Portuguese people.