I'm off Millikan and Amazons direct couriers have been an order of magnitude more reliable than my UPS driver (who doesn't follow my delivery preferences and takes my stuff to random UPS stores that I have to pick it up from).
Corporate policy, Access Point after 1 attempt is cheaper than 3 attempts when the resident is likely at work anyway. Driver release (most situations where the package is left at your house and the shipper didn't explicitly authorize it) is at driver discretion, it's their problem to a degree if something gets stolen.
I can kinda get the incentive (saving time) on signature-required packages, since it's faster to slap a label on the door than wait for someone to answer and sign for the thing.
But why do they do it on non-signature packages? It makes no sense.