Don't be so quick to blame the letter carrier. I don't know about Canada but in the U.S the mail is sorted and bundled and the carrier basically puts the bundles in the box. The actual sorting is done at a remote station. The carrier really doesn't have to look at the mail. If it's a large parcel then it's a little different because it has to go in another box and they should be looking at it but small boxes that fit in the regular mail boxes don't get that scrutiny.

I've had plenty of cases where the carriers are supposed to get signatures and they don't and plenty of times where they just put a notice to pick it up at the post office without knocking on the door to get a signature.