The article didn’t use any examples from outside the U.S. It seems like more of a class issue. In America, white people are more likely to have the money to go to college, and a college degree means you’re more likely to get a white-collar, 9-to-5 job with a better income, which means an easier, more secure lifestyle. Like, imagine being married and driving every day to a 9–5 job in an office where you sit down at a desk. Then imagine being a single parent taking the bus to two jobs at odd hours where you stand on your feet. Obviously the first person will get better sleep.
White people are more likely to have the advantages that put them in the first camp. Not getting enough sleep is just one more shitty symptom of a society that favors white people, but there are exceptions. I’ve had jobs that started at 5 AM or ended at midnight, and I’ve done all combinations of working two jobs/ school and working/ working overtime in retail and restaurants and relied on public transit. Nowadays, my schedule is actually pretty reasonable and I drive to work, but it’s easy to understand how economics can play a role. When you’ve got bills to pay, sleep is less of a priority than making ends meet.