Tip is optional and you can change your tip amount within 48 hours of delivery. I'm not sure if drivers can see what the customer tipped during the delivery but in case you feel that they might do a shitty job because of no tip you can just add a tip and then change it to 0.
With that being said I'm also not feeling the whole tip thing because the wages should cover all that.
I've ordered a few times from Prime Now and so far it's been a pretty good experience. I like how it shows real time GPS tracking of the delivery driver as well as the name of the driver.
I've put specific instructions on where to leave the package if I'm not there or to give me a call when they've arrived, and so far no problems there. It's pretty easy to associate the courier as a courier since a notification pops up saying the driver has arrived and you can see the person holding a big brown bag with an amazon label on it. Pretty straight forward imo.
So far a much better experience than OnTrac leaving shit wherever they please.
With that being said I'm also not feeling the whole tip thing because the wages should cover all that.