Transferring Apple Card to a different phone with a different Apple Account

You can change the email address and password and still maintain your associated Apple Card Mastercard. However, the Apple Card Mastercard can never be associated with a different account.

The email address you use for your Apple Account is basically your user name and the password is, well, your password. Both can be changed, but the card/account can never be moved. It’s an antifraud precaution.

No. You would have to sign in to the same Apple Account on the other phone.

So why would you create a different Apple Account (formerly Apple ID) for a different iPhone instead of logging in with the same Apple Account you are currently using?