As usual, i see you make unique suggestion/idea on technical board. I can't wait coffee shop require 6 (5 + 1) confirmation and exchange require 11 (5 + 6) confirmation, once your idea implemented on Bitcoin network.


Jokes aside, people already can "undo" or "cancel" their unconfirmed transaction thanks to existence of RBF and full-RBF. They just need to use wallet which support such feature, such as Electrum.