So every single package is hand delivered? That's crazy to me.
That is a special service here usually requiring a signature. They are uncommon.
I worked in logistics. I am not exaggerating when I say you have seconds per package on your route, and no I don't just mean Amazon. Waiting 2 minutes at every door to wait for someone to answer would mean we'd need 5-10x the staffing.
How does that even work? 95% of your customers are going to be at they're own job not sitting at home.
When I worked for USPS the number ~8 seconds per mailbox. Not an exaggeration.