Why is the actual ride fare sometimes different than the estimated fare?

When you enter a destination, OMNI’s software provides an estimated fare based on the rates of the drivers most likely to accept your ride request. Estimated fares are typically identical or very close to the actual fare; however, during very busy times when there are fewer drivers available, actual fares may vary a bit more (often they are less expensive) than the estimated fare. When your driver accepts your ride request, you will be presented with the actual fare at the bottom of the screen. You can cancel any ride without penalty for up to 3 minutes from the time your driver accepts your ride request.