If everyone had to confirm their bids and plays, this is now only an option, there would be no need for undoes. Undoes cause many problems. They give unauthorized information to partner. Many people think they have the right to them and boot you if you reject. Or they ask 50 times until you leave the table. Many people do not understand undoes are for mechanical errors only, they think they have the right to change their mind. And tell their partner they want to change their mind!! To repeat, undoes aren't really necessary. Just remove confirmations from options and make them part of regular play.