I'm wondering why matching is nontrivial. When I use these services, it doesn't always give me the closest car of the ones shown. It's all about which driver a

I'm wondering why matching is nontrivial. When I use these services, it doesn't always give me the closest car of the ones shown. It's all about which driver accepted my request first. Isn't it a fairly easy calculation of "all cars within X km or the nearest Y cars", and then whichever driver taps first gets matched with you?