Possibly because of the increasingly poor service.
Can you elaborate on this? What was better about your service in the past in comparison to now?
One of the most common complaints is probably "the postman left a card but I was in, he didn't knock" which almost every time is simply rubbish. There's more work involved in leaving a card than there is in attempting a delivery.
At least when they do
leave a card I have a chance of actually getting the item by going to the delivery office -- OK, it's a 20 minute walk, but I can get there. If it's a private firm it's probably gone to some holding depot that I (as a non-driver) can't get to, because it's in the middle of nowhere and/or it doesn't open at weekends.
If I expect something to be sent by courier, I have it directed to my work address so somebody on the front desk can sign for it.