Surely most customers would benefit from knowing that they’re bidding for service? Don’t call it a tip, but a bid or priority fee.
It doesn't help with situations where drivers are multi-apping (accepting orders across multiple apps and juggling them). The drivers don't even know you have priority.
edit: and in the US where you can definitely see the tip up front, you will almost always find that the order will get picked up quicker if you increase the tip by the equivalent of the priority fee. But you may well get stuck with a delivery before yours.
It's wild because this happens maybe 10-15% of the time for me when I don't choose priority, but it's around 80% when I do.
I ignore the option now and just bump the tip if I want a chance of better service.