In the end they have to pay for all the maintenance and initial purchase of the vehicle as well even if they manage to put those on the driver's as well.
Their "independent contractor" employment model doesn't work in some markets where they end up paying regular benefits and taxes.
But also, Uber is a valley tech firm, meaning it has extremely high overheads. To service all those markets Uber employed 29,300 people last year, a roughly 30% increase from 2020, and note that isn't including the drivers. That's nearly 30,000 people in operations and software development of various kinds.
Uber probably can't make money even if it stops subsidizing rides because the extra added value of a ride-hailing app (which is certainly non zero) is nonetheless not enough to offset the cost of having such a massive company, especially given that so many are earning some of the world's highest salaries.
How can they not be profitable after all these years.