When the demand for rides is high (e.g. peak hours, large-scale events, extreme weather conditions, etc.), rates are increased to encourage drivers to get on the road.
When prices are increased, you will see an arrow pointing up next to the trip price. You can check the rates for each category by selecting it and clicking on the vehicle icon.
Due to the changes in rates described above, a journey from one specific location to another may not always be the same price.