That's not what scheduling an Uber actually does, though.
"The Scheduled Rides feature allows you to select a 10 minute window for a driver to come pick you up. At the start of the window, the app will send out a ride request on your behalf."
So if you "schedule a ride" at 7pm, it is exactly the same as just using the app manually at 6:50pm. There is absolutely nothing remotely close to a guarantee that anyone will you pick you up at all, much less at the time you chose.
Not exactly for Lyft when I drive for them. Scheduled ride is a priority request that will go far out of the area. Lyft will happily ping a driver from 30+ miles away 30 minutes in advance. It will also pull a driver from the virtual queue at an airport.
In my case, there is no way there are going to be drivers available at 4am to take me 45 miles to the airport which is fairly typical of what I need. There are barely drivers available to do it during the day and cancelations for going into the city are not infrequent. I just use a private car service even though it's about 2x the price.
Three days ago I scheduled an Uber for 5:00AM-5:10AM.
It arrived at 4:57AM.
EDIT: Perhaps you misread the description...
"The Scheduled Rides feature allows you to book a trip in advance by selecting a 10-minute pickup window. The driver will be requested on your behalf and will arrive in the 10-minute window you've selected. In the case where a driver is not available, you'll be notified."
There would be little sense to doing what you suggested (queueing rides 10min in advance for scheduled riders) because Uber can use scheduled rides as constraints for pathing of vehicles, and some areas would have a greater than 10 minute wait time for pickup.
I think we did a Lyft once where we scheduled the night before and a specific driver accepted the ride that evening, then showed up at the godawful time in the morning that we specified. It was basically like arranging a taxi, but through the app. Did that feature go away or get changed? It was a year or two ago.
But if you schedule a ride for tomorrow they'll wait until the time of the ride and then look for drivers. It's handy if you might forget, but it misses the most handy part of the old model: they'll either tell you yes or know, and then you know ahead of time if it'll be possible to get a ride.
Neither Uber or Lyft will even tell you if historically drivers have been available if you request a weird time. In some places you can call an Uber at 5am, in others that'd never work, and figuring out which requires local knowledge which runs contrary to the whole point of Uber/Lyft.
I've never used uber/lyft. While I watched the movie Stuber, the protagonist had never used it either and tried using it like a taxi. I felt like an out-of-touch old guy learning how stuff works along with him.