What's the purpose of the pin?

I usually have good experiences with The Courier Guy. Not that I use them often, but mostly can't complain. Today, however, I have come across an issue which I feel is quite concerning.

I placed an order with a company and they sent my package with the Courier Guy. I live in Waterfall. I got an email to say that my package had been dispatched and they gave me a pin. I was expecting my package to arrive today. I then received another email saying my package was delivered and that the pin had been used successfully. This is false as I had been waiting at home all day and had not seen any Courier. So I called them. The phone rings and rings and no one answers. So I used the whatsapp feature. After a couple of messages, the lady I was talking to asked me if I had changed the delivery address from Waterfall to Springfield Park. At this point, I realized there was a big problem so I asked her if I could call her rather than chat over whatsapp. She gave me the number to call but, again, it rang and rang. She eventually asked for my number and called me. She explained to me that the package had been taken to the correct address but in Springfield park. The receiver didn't have the pin so the driver asked for their number and sent the pin to them. After receiving the pin, he handed the package over and went on his way.

In my opinion, this is a huge issue. What is the point of sending me a pin if the driver will just give the package to anyone with a cell phone? Neither that person's name nor number was on the package yet he handed it over without question. This is unacceptable.

She told me that he would go back and collect the package this afternoon but I would only receive it tomorrow. I told her it's inconvenient for me. It's not my fault yet I am punished.

They keep apologizing for inconvenience but I would like to know who authorized the change (I double checked and the address I provided clearly says Waterfall) and how can they give the package to any random off the street? Who will pay for my missing items if the original receiver opened the package and removed anything???