Complex sentence: Gun politics are thus not the major issue in Mexico that they are in the nearby United States, since few Mexican citizens have any gun law difficulties, and, usually, only US citizens run into trouble with Mexican officials over gun politics.
Split into simpler sentences: Gun politics are thus not the major issue in Mexico that they are in the nearby United States, since few Mexican citizens have any gun law difficulties. Usually, only US citizens run into trouble with Mexican officials over gun politics.