People shouldn't get paid in tips. The fees should go up to cover cost-of-living and hazard pay, or at least until there are enough shoppers to cover demand.
I should be able to get reliable orders with $0 tip. I shouldn't pay less, and people shouldn't get paid less; it should go into the fee.
If it is a tip, I should have control. One shopper got me the wrong bag of food. If tips are there, tips are intended to manage that, not to bribe someone into taking an order.
There are legitimate reasons to lower a tip. Tips should come at the end after the service is rendered. If the shopper is aware of it ahead of time it’s more like a bribe than a tip.