Alexandra Rodríguez Urbina, a young nurse in Caracas, has not had a day off in nearly two weeks. She moves between clinic and hospital shifts, starting before sunrise and often finishing long after dark. At night, if she’s not too exhausted, she bakes cakes and cookies to sell the next day to patients and colleagues. When she finally gets a day off, she spends it at the supermarket. Before going, she makes a list: vegetables, chicken, eggs, milk, maybe meat or sausages. But the list rarely holds. Prices change quickly, and what she can afford one week can slip out of reach the next. Ms. Rodríguez no longer shops at her usual supermarket; it became too expensive last year. She now goes to a cheaper Chinese-run store, adjusting as she moves through the aisles. She picks up a package of sausages, checks the price, and puts it back. At the meat counter, she takes a number, hesitates, then leaves. This week, she decides, it will be chicken and legumes.…