PINs are very costly because every time someone forgets one, you need to do an identity verification which usually depends on a human employee of the bank.

I'm in the UK and I forgot my credit card pin a few years back. Getting it sorted was as simple as phoning an automated phone number, entering my card details and they then posted a new pin to the address they had on file. I highly doubt there was a single human involved in the entire process, and it was probably just an add to their lost card procedures.