Why not just ring the doorbell to let me know you’ve left an expensive parcel on my doorstep?

Why the hell do some delivery drivers simply use the doorbell to let people they’ve left an expensive package on their doorstep, instead of knocking gently on the door, taking a picture of the parcel and marking it as “delivered”?
It hasn’t been “delivered” it’s been left on the doorstep, there’s a difference.