This may be someone who is new.
I once had a grocery delivery, the guy called me to say he was arriving with the groceries. I said great thank you, he said Ok, and we ended the call. I waited behind the door (leaving it closed) for him to drop it off and leave because it was when the pandemic was in full swing. I hear him walk up on the porch, then there's a couple minutes of shuffling, where I assumed he was taking a picture and setting things down, then I heard him pull away, and I opened the door to grab the groceries, and found nothing. Confused, I walked around looking even behind bushes. I was behind a wooden door so I didn't see him, but I clearly heard him step onto the porch so what could he have done with them?

I looked for several minutes, and called him. No answer. After a few minutes, I call again, and tell him to please tell me where he put the groceries, he said I didn't open the door, so he drove them back to Walmart. I told him I answered his call, and my instructions are to leave it on the porch, why would he just leave with them? He said again, I should have opened the door, and he thought I was rude to not open the door (in a pandemic). I called Walmart, they thought the guy was nuts, told me he doesn't understand what "no contact delivery" means, and they sent someone else out with the groceries, but the ordeal took another 30 minutes and by that time my frozen stuff was thawed.

My instructions were to leave on the porch btw.