They could let customers pay a N% (say 10%) premium for a ...better-rated delivery courier? I'd be curious to see how that'd A/B test. Probably would fail, but nonetheless prove a point if there's any 'service' component that is possible to compete on.
I believe Uber eats is currently doing that. Recently I noticed an option to pay $1.50 extra for "Priority delivery" which may be a combination of what you mention as well as modifying the delivery algorithm in your favor.
