Passengers should never cancel accepted trips. That's what I explain to my passengers when they complain about other drivers doing this.
I never cancel my trips if the passenger is ready to go (some are too drunk or otherwise unable). Drivers who cherry pick can still be reported, but that's a manual process.
The leading cause for driver deactivation is excessive cancel rate. For that reason, the passenger should insist that driver cancel the trip.
I run into this when I call the passenger to confirm that they indeed wanted to order Plus service and that they are willing to wait 15-20 minutes for me to get there. They often think I am calling to cancel, but I never ask the destination since that's at least unethical and possibly illegal.
Maybe I don't understand what makes a good fare.
Also incentives are based on trip count, not trip length as far as I understand.
It's a problem that needs to be fixed in big cities with these apps.
But the reason why they reject in these cases has nothing really to do with the person, but the action/destination. Definitely an improvement.