Originally Posted by john2g1

Uber/Lyft/.... is different from a restaurant. No percentage is required it's more about literally showing gratitude (gratuity) for the situation you put your driver in.

Your in a rush and driver significantly beats ETA: small tip (like a buck or two)

You made the driver wait almost the entire 5 mins: small tip (late rider cancellation fee is $6 for UberX)

You asked the driver to wait for more than 5 mins: tip $3-5 for every 5 mins you were late

Your late for something expensive (flight/you're going to be fired/etc): tip for the extra gas driver burned getting you to you destination + gratuity for saving you
Seriously if boarding starts in 50 mins and it's a 50 min drive and the driver turns it into a 30 min driver tip well. Airport late rider change fees range from $50 to a new ticket. Tip really well

Driver loads bags/groceries: small tip ($1-2)

Driver loads 50 lbs luggage: avg tip ($5)

Driver loads 60+ lbs luggage: big tip ($10-15)
Most airlines charge and extra $50-125 for severely overweight bags

Aux cords, phone charging, anything that makes the ride more like a limo than a taxi: small tip ($1-2) per amenity used

This isn't mandatory tipping rules but drivers get put through these kinds of things daily.

The job is to be at A. at X time, safely drive to B. along the GPS suggested route within X time as per/GPS. Drive from A. to B...

Anything that goes above and beyond that the rider SHOULD show gratitude.