Right now the only way to make transaction is through shops or 1 on 1 trades at local spawn. Sometimes you just need to pay debt but the other player isn't on or you need a pet where you are (ex. cats for creeper farms) and don't want to go to local spawn to pay the other player. Introducing WilderWallet. This item requires both players to own it to be able to work. Player 1 can request or send any sort of payment to Player 2 digitally, without having to meet anywhere. A nice extension would be being able to declare that you are in debted to someone and a percentage of the diamonds you earn through your shop would automatically be transferred to the other player.

I think I get where you are going with this, but it just sounds like a ton of work for something that might not get used all that much.

Players can already setup a mailbox in their shop....put a hopper into a chest in the ground and players can drop anything into it that will wind up in the chest. Bury the chest and it's only accessible to the shop owner.

The auto-payemnt thing sounds nice, but again, how much does that really happen?