My new hobby is to sell things on the local FB page. The way it’s done in this area is very typical and never fails to freak out newcomers to the region. The way it’s set up is so that human contact is avoided as much as possible. You are supposed to leave whatever you are selling on the porch. Buyers will pick it up and leave money under the mat.
If you see people approach and come out to say hi, they get very spooked and react like you’ve committed a huge social faux pas. Sellers prefer to risk never getting any money (because nothing is to prevent buyers from not leaving money under the mat) if it lets them avoid exchanging a few words with human beings.
Of course, I like finding cash under the mat every once in a while but it’s still creepy how scared people are of human contact. I mean, for me to find it excessive, it’s really got to be something quite notable.