Not sure if this is the reason, but, I had a USPS package to be delivered to me, had a tracking number and it showed it was "delivered" on a particular date but I never actually got it. Come to find out that the mail carrier person could not physically drive up to my residence mailbox because another car was supposedly blocking it or in the way of the postal vehicle approaching the mailbox. I was informed that postal regulations require a curbside mailbox to be unobstructed to thirty feet, else no mail will be delivered at all! My problem was then why would the tracking info state the thing was "delivered" when it was not, blah blah blah.