The fact that Lyft takes a different percentage of each ride -- from less than 20% to more than 70%, in the author's experience -- is a reflection that at different times of day, on different days, in different locations, there are different mismatches between driver supply and passenger demand.
Lyft obviously pays the minimum needed to ensure available drivers, and charges the most that passengers are willing to pay. None of this is surprising -- it's how a market intermediary works. As more drivers sign up and are active in relation to passengers, driver pay decreases. As more passengers need rides in relation to drivers, passenger fares increase. And vice-versa.
The idea that taxi dispatchers could be more efficient, or as efficient, is ludicrous. Does nobody remember regularly waiting 30-60 minutes for a taxi from a dispatcher?
To answer the author's question, of course Lyft could make deeper cuts while keeping the core business running. But most of running a business is about reinvesting profits/capital into growth when growth seems available.
After all, the very first sentence on Wikipedia makes it clear all the things it's trying to do at once, of which ride-hailing is one of many [1]:
> Lyft, Inc. offers mobility as a service, ride-hailing, vehicles for hire, motorized scooters, a bicycle-sharing system, rental cars, and food delivery in the United States and select cities in Canada.
It takes a lot of employees to be doing all those things.