It is tricky, because I REALLY HATE TIPPING CULTURE. But I also DESPISE situations where people are not given a fair wage.
I don't think any of my delivery-folks are in that situation, they aren't "independent contracters", they're employed by AusPost, or Toll, or Coles, or Dominos. At least, they wear the livery.
(No, I don't get things delivered by Uber or any of those "gig contracters" -- not after my one experience with Uber ended up with me being incessantly spammed.)
Unless I'm mistaken? Are they all bit employees?