I think comparing Mexico to most US states, as well as to other countries, is comparing apples and oranges. The problems facing Mexico, as well as a lot of third world nations, have less to do with guns and more to do with economic problems and political corruption. If you arm every Mexican overnight I don’t see it solving their problems.
Crime doesn’t exist for it’s own sake, it exists because of economic issues, drug problems, social issues, etc. Arming more people won’t make those things go away, just like taking away guns won’t make those things go away.