Quick question

I have a question. When buying flowers, there's no lock feature to protect the seller's Ingots, so if you agree to trade flowers with someone and the seller sells them at a low price, someone else can just take them. If you accidentally clicked on someone else's flowers, you'd apologize, return the flowers, and lock them for the designated person, right? So why can someone so confidently say they can just take them because there's no lock? They demand double the price to return them, without even apologizing, saying it like a favor: "It's only natural you'd get double the Ingots from me, right?" They say they can return them tomorrow with a certain number of uses, but you were the one who said you don't remember, and you were the one who said you'd give Ingots and sell them for double the price. Why not discuss it? Am I the fool for taking the flowers back at double the price? Should I just accept that my hands were too slow? That doesn't make sense.