As military coups go, Thailand’s putsch on May 22, 2014, was rather polite — no mass imprisonments, no stadiums full of students tortured and shot. The toppled prime minister, Yingluck Shinawatra, was detained for only three days. Before the coup, there had been months of street clashes between loyalist “red shirts” and opposition “yellow shirts,” and now General Prayuth Chan-ocha’s junta promised to “restore happiness to the people.”

There have since been some public protests against martial law. Students were arrested in Bangkok for flashing a three-finger salute copied from The Hunger Games, the novel and attendant movie about a rebellion…