[Defeat]

How will the delivery driver proof that they actually dropped off the product? They could have stolen it.

They're not dropping It off, but rather waiting for a member of the household to accept It after they knock on the door:

its teams will place the parcel at your door. Having knocked on the door, the delivery teams will step aside to a safe distance while the item is retrieved.

The operative words are:
while the item Is retrieved

Meaning they'll await for a household member to personally accept It and If they neglect to do so, the delivery Is redirected to a local collection depot.

What if the SEer took it, and the delivery is marked as complete. Then said SEer denies they have taken it. How would the delivery driver be able to proof they didn't just take it for themselves and pretend someone took it?

Do you use PayPal for payment for curry's PC? If that is the case, I would be hesitant about thinking DNA would work with certainty if it fails with the merchant. I say this because I often think of PayPal as a safety net and sometimes it is for failures, but PayPal only cares about the tracking confirmation and nothing else.