...I don't know how someone can find the details of passport just using the bank account, Do we link our passport while creating a bank account? I didn't until now...
When you receive a payment card, you need to pass KYC in the Bank. This way you can always be identified by your account, as they are always linked to your documents. If you buy bitcoin through a centralized exchange, you can always be identified using payments made using a Bank card.
Ofcourse banks will know our details to ensure we are using their services for legal purposes but how the exchange can access our details? Is this available for public access in your country?