$50b in revenue last year is nothing to scoff at. They have levers for profit but instead re-invest every dollar. Your argument sounds exactly like what people said about Amazon years ago.
For example Uber's last quarter revenue was $3 billion on some $14 billion in bookings, with a loss of about $800 million.
$14 billion is revenue
$3 billion is their earnings after driver costs.
They do that specifically to reduce their running costs and hence maximize the profit on their actual revenue.
That would be like saying all iPhone App developers are working for Apple, when in fact all Apple does is take 30% of each and ever dollar these App developer earn in sales.
Likewise Uber just puts it's 30% Uber tax on every dollar it's drivers earn.