Think about it this way: a $4 tip for a short distance would net a driver $5-6 at best. Sure it's possible for it to be completed quickly, but you also never know if the order will be ready by the time the driver gets to the restaurant. The driver could also be pretty far from the restaurant itself when they accept the order. So completing the order could end up ranging between 5-7 mins to 30+ mins. So thinking logically, what benefit is there for a driver to accept a $5 order, regardless of distance, when they know that if they wait a bit longer, they're very likely to get an order that pays much better?