Did you pay cash or via credit card define in the app?
I paid via credit card. So far ok coz I received emails showing the fee after 50% discount. So the drivers did not anyhow drive off without completing my ride on his app.
But I have not receive my monthly statement, don't know got any weird surcharge for using credit card outside Singapore.
Ya try Grab car in JB cause its a fixed rate, even driver anyhow drive long route or stuck in heavy jam, we pay what is reflected when we book. Don't have to worry that drivers purpose take longer route, and I am sure they will choose the fastest and shortest route cause they also want to save petrol and time to pick up more passengers. Uber more ex as less uber cars and app so unstable. Try log in both apps to get the estimate costs next time u try grab/uber in JB.