The drivers don't know in advance what tip they're getting, do they? Doesn't seem to be the case on UberEats, anyway. Failure to tip will eventually result in fewer available drivers and later/colder deliveries, but it's a statistical thing rather than an individual consequence.

I live out in the middle of nowhere and consider myself lucky that they deliver at all, so if the food is a bit on the cold side I don't normally take it out on the driver. I've had other complaints with UberEats, but overall the service works about as well as can be expected.

I have tried tipping, then removing the tip after the delivery, same stuff.