I've ordered expensive things from Amazon to my office in the US and they did the whole code ritual... the driver just dumped it at the door and ran. It's all for show.
Over here I was definitely told by Amazon drivers that unless they type in the code it won't mark the parcel as delivered. The same with GPS trace - unless they are within ~100m of the destination it won't let them actually mark it as delivered. Maybe your driver didn't care about having missing parcels at the end of the day, but the system is strict about it(again, over here, maybe Amazon US is different).