It would be interesting to learn the view of fellow drivers. Having driven some distance to the pick-up point, you have already used up none earning time and there is some vehicle and fuel usage to consider. At the pickup point the passenger approaches your vehicle and says that the other person(s) is on their way so won't be a moment. You discuss the destination, so everyone is happy. Now that you are sitting at the pick-up point, know the destination and you could find yourself sitting for a further 5 or 10 minutes or even longer, at what point do you 'start' the trip?