From this article [1] posted a few days ago, TC says 34% (Uber is at 66%) and that's due to running at a larger loss by offering discounts to riders. Gaining 4% market share is no small feat but doing it by giving discounts isn't exactly a long-term vision.
Market share means drivers stay busy and make money. Market share means riders don't have to wait a long time.
Uber gave massive discounts for a long time to establish their market share, and it suited their long-term vision just fine.
Same strategy seems to be working well for Lyft, too.