Mexicans elected Andrés Manuel López Obrador president in 2018 for sound reasons; his diagnosis that inequality, insecurity and a corrupt political class were damaging Mexico was convincing. But apart from poverty-reducing minimum-wage increases, Mr López Obrador’s “Fourth Transformation” has taken Mexico backwards. A statist, bent on tearing down the works of his predecessors, he is leaving the health-care and education systems in tatters. His reversal of pro-competition energy-market...