A handwritten price can begin a conversation that a polished display would end.

Polish tends to close things off. A printed price with a barcode says the matter is settled, while a number in biro on a bit of card suggests a person set it and a person could discuss it. That is not really about money; it is about whether the arrangement looks human enough to be spoken to.

Look at where you have made something too finished to be questioned: a document, a plan, a room. Leaving visible seams invites the response you actually want. If you want people to talk to you, let the surface look approachable rather than complete.