It's not surprising to view the Mariachi uniform as similar to a military one. The metal buttons and golden embroidery (albeit slightly more flamboyant), sharp lapels and short jackets. It all stems back from the Spanish colonial days apparently.
This band were playing in a courtyard for an event which had 25ft high paper mache puppets called Mojigangas being walked around. I would've photographed those but they terrified me!