Although they are in general quite bad, in my local area they are surprisingly good - for one reason - that specific delivery driver has significant local knowledge.
Getting the right staff in the right place sometimes makes a big difference.
I think it's that they give the delivery drivers a stupidly short amount of time to make deliveries, so it's up to each driver how they handle it.
Some take their time and work slower, some leave them buy your front door and don't ring the bell, some dump them over the fence, and some just mark them as delivered and drive home with the parcels.
Getting the right staff in the right place sometimes makes a big difference.