To make shops safer when there are multiple customers (as some could just steal the items being traded). Perhaps there could be a command where you give what's in your hand to a player? So if you have a stack of cobblestone, /hand [PLAYER] would put the stack of cobblestone in the player's inventory in the first available spot, similar to if you pick it up (meaning trading less than a stack would combine with the current part-stack in the recipient's inventory). If the person has no space in their inventory, it will come up with an error saying so. Oh, and to prevent trolling and spamming useless items to people, you have to be within a certain radius of someone to be able to send them something. EDIT: And the recipient will get a server message saying "[PLAYER] sent you [ITEMS]!"
How would this stop scams? It is like dropping the item just sending into their inventory. That's to prevent people stealing but people might not pay up if it's for a shop.
I've seen ideas like this all over the place, don't feel like digging through posts to find it. I've said it before but I'll say it again, I only kinda support this because I feel the current trade system is okay. As someone having a shop on my island, I know to only trade with those I trust, and those willing to comply to shop policies. Just doesn't sound too necessary.
50% support. It would be nice to prevent stealing, however maybe there is like a chest or something that you put your stuff in, and the other player can't take it out until they have put their item in.