Buyer No-Shows Pickup Time, Flabbergasted It's Sold

Why do people have such a hard time with this? People have a a whole lot of difficulty communicating reasonably or responsibly when buying and selling stuff to strangers, which is how we get moments like this seller who's not falling for BS and a lowballer who gets weirdly classist or this artist who isn't having a lowballer who refuses to pay for completed work.