Ride-hail companies have entered a new era, marked not by breakneck growth but by skeptical and emboldened regulators. Cities lost the first round against Uber, which strong-armed them into passing rules it wrote to suit its ride-hail service before anyone could figure out what was happening. Now, cities have regrouped and are flexing their muscles. One by one, Uber’s most important markets—London, New York, Los Angeles, San Francisco, the entire state of California—are proposing taxes and rules that one way or another make rides more expensive.