Even if 90% of Uber drivers drive <10 hr a week, its quite possible that more than 90% of the total ride time is be drivers who drive ~24 hrs a day.
In India, most Uber drivers I spoke to had a common thread. They buy new car, slog day and night to pay off the monthly payments, which means sleep for 3-4 hrs, work for 12 - 14 hrs.
Sleeping they do, wherever they'd find a safe place to park the car, and sign out of the Uber app. Basically no life of their own, until they pay off the car.
For many, lured by Uber's scheme of 'leasing to buy' cars scheme, once they have had the car for a month, its difficult to get out of that scheme because of loss aversion, and hope of independence after slogging for 3 to 4 years.