Could not have put it much better myself. When I did my last driver day out we had a similar one. Drive up to property. Park outside in big orange van. Walk to door. Ring bell. Wait 20 seconds. Knock. Wait another 30 seconds. Walk back to van. Get "Sorry we missed you card". Walk back to house. Knock again. Write out card. Post through letterbox. Door opens!
"Trying to run off were you?"
WHAT? We've been loitering in your front garden for the best part of 3 minutes and only now you decide to actually take notice?
In my experience, the vast majority of people who say "Oh the driver never knocked/never attempted" are either liars or deaf.
I regularly get stories like "I watched your driver from my window walk up to my front door, stand there for a minute, and then walk off and drive away in his van"
Great. So why on earth did you not just go and open the sodding door!? Seriously, people are mental.