Last September, New York City began enforcing its strict new regulations on short-term rentals. Since then, the number of legal short-term rentals listed on Airbnb and other platforms has plummeted. Less than a year into the city's policy, known as Local Law 18, it's not clear whether the near-ban is achieving one of its central goals: relieving pressure on the city's severe housing shortage. But as summer tourism heats up, the dearth of rentals and rising hotel-room prices mean visitors to...