Given their resources and presumably some sort of ability to test how does stuff like this persist?
But your thesis isn’t that obvious to me; what is so confusing about it? You need to be very specific about these sorts of questions. As for the countdown, it just covers the time needed to send a request to the nearest driver and have them accept the trip or not. Lyft cannot simply assume that they’ll accept because they might be planning to take a break or even end for the day after finishing their current trip. The countdown can only ever be approximate, because the driver is human. Lyft can only guess how long it will take them to read the message and make their decision.