Estimate rideshare fares.
Rideshare fares are charged on distance AND time simultaneously, which is why an identical route costs more in traffic. Splitting the two components shows where the money goes: on a fast motorway run the distance term dominates, while in stop-start city traffic the time term can overtake it. The effective per-kilometre figure lets you compare trips of different lengths fairly, since the base fare weighs much more heavily on short hops.
Fare
fare = base + distance x per-km rate + minutes x per-minute rate
Effective rate
total fare / distance
An estimate only. Actual fares depend on the operator's current rates, surge pricing, tolls, waiting time and minimum-fare rules.
Because you were charged for more minutes. Traffic increases the time component while the distance component stays the same, so the same journey costs more at rush hour.
The base fare and booking fee are fixed, so they are spread over very few kilometres. That is why the effective per-km rate falls sharply as trips get longer.