MEXICO CITY—Mexican President Andrés Manuel López Obrador returned to his daily morning news conferences Monday following a two-week absence after catching coronavirus, but vowed not to wear a mask or require Mexicans to use them. “There is no authoritarianism in Mexico … everything is voluntary, liberty is the most important thing,” López Obrador said. “It is each person’s own decision.” López Obrador revealed he received experimental treatments, which he described only as an “antiviral” medication and an anti-inflammatory drug. The president also revealed that he twice tested negative in late January in rapid tests that are widely used in Mexico, before a more thorough test—apparently PCR—came back positive the same day. “I came through well, healthy,” López Obrador said, noting he had been doing breathing exercises as well. “We are back on our feet again, in fighting style.” Many residents of Mexico City have been unable to find beds at …