Not just us then. We have two bells, one upstairs, one down, on a proper hard wired transformed from the mains set up and no knocker on a very solid wooden front door with great big brass bell push next to it. Still they insist on knocking, when they do the first thing I do on opening the door is press the doorbell and say "oh it is working, I thought it was broken when I didn't hear you ring it" That keeps them waiting for a minute before I sign for whatever. Some delivery guys even find their way around to the garden door into the lounge and knock on that where we have no chance of hearing them if we are upstairs or in the kitchen.
Mike