[biafra]

Wouldn't the criminal in this case be able to intercept the letter with the PIN also and replace it with a letter that looks the same but has the wrong PIN? The receiver would not be able to find out the PIN is wrong because the cards chip does not work at all.

[gambiting]

I have never received the pin by post. My bank sends me the card, then I have to go online to activate it and set the pin on the website - the card never has a pin assigned to it by default.

[juvinious]

Pins are generally mailed separately before after mailing the cards. (In this case I'm speaking of debit cards) It might make it difficult to map the pins to the chips, but maybe not since it seems these are bulk mailings.

[doikor]

Some banks allow the user to choose the pin when ordering the card so they can save the postage on one extra letter.