It seems like this does not happen all that much? If this is true, Bravo! Dealers and users CAN be honest when the stakes (LE, violence etc) is minimized. Or is that the truly depraved drug addicts and such are not tech savvy enough to understand the DNM. I am just very pleased a civil marketplace like this exists.
I think they get ripped off a lot more than they let on, but they eat the loss, or have somewhere private to vent about it. So many people claim lost packages or late or underweight. I know some shady vendors can easily send something to the recipients zip code, prove to admin they sent the package and win dispute.
If you stick to solid vendors, who have good feedback, neither party will get ripped off. For example I had a question about an order; just seemed underweight, I figured I ordered the wrong pack to the wrong address, and with no hesitation they sent out reship. I wont mention the vendor so they don't get this good will abused.