Choosing the driver
You choose before sending, while the customer is on the line.
As soon as the pick-up address is resolved, the fleet list narrows to whoever is free near that point. For each one you see how long they take, which fare applies to them and what the job would come to.
The driver is chosen before the request is sent, not after. On the phone you have to be able to say “I am sending you Mark, four minutes” while the customer is listening: a job created with nobody on it is a promise made without having booked anything.
Until the driver accepts, the job stays waiting and is not assigned. It is the difference between promising a car and having one, and on the dashboard you can see it at a glance.