Let's say you know you've got to be at the airport at 9 o'clock in the morning. The planners among us would call the airport while the coffee was brewing and ask for a cab to be sent over at, say, 8:15 a.m. The truly anal among us would call the night before. Those grasshoppers who trust the universe to provide for them would just stand at the curb at 8:30 a.m. and whistle real loud.
Uber doesn't really allow for any of that. You can only hitch an Uber ride via the service's app, and you cannot call ahead. You check the app a little before you want to leave and click on the next Uber driver who can get you there on time. No calling ahead, no whistling at the curb.