Anything that delays them means Uber burns more cash subsidizing cheap prices to hold back competition.
And once they do arrive, competitors can enter the market with lower costs.
Or, maybe Uber isn't losing as much as it seems? (Estimates are $2+bn/yr) Or there is some moat that protects them? I just don't get it.
A while back another user did this math using leaked financials from Uber and Lyft and Lyft deserves more criticism for subsidizing rides than Uber:
Subsidies don't work at scale. The bigger the ridesharing market gets, the less a company can meaningfully provide a subsidy that changes consumer behavior. Whichever company can get to breakeven before R&D and capital investments are taken into account is going to clean up because at that point they can outlast their competitors indefinitely.