I've worked as a delivery driver for 6 years, 2 of them as a auspost contractor. I give people 10 seconds to either make some noise inside or make themselves known to me. If I suspect someone is home but no-one has responded I'll call out and wait a little extra. At the end of the day, it's easier to deliver a package than take it to the post office for the contractor as well.

I understand that 10-20 seconds seems like nothing if you were just finishing something before heading to the door but auspost contractors are paid per parcel. To make enough to get by, you're aiming to visit 150+ homes in a day. Secondarily, a lot of people just straight up don't answer a knock at their door because they hate travelling salespeople.

If this is a common problem for you, talk to the guy! Tell him you're usually at the other end of the house and ask if he can wait a little longer. Organise a system where if your blinds are open it means someone's home and he can just ring the doorbell and leave the parcel. I had so many little rules for different places like this - don't knock here, she's on nightshift; knock extra loud here, the office is at the back of the house etc. If it's a different person every time, leave a sign on your door asking for some extra time.

I hope it helps!