I basically agree with you, but it's not like you could not be tracked using your credit card number.

This is not about tracking, having your biometrics means they can resell the data to other providers (e.g. palantir or some other hellish enterprise). With that, the places and means of following you in real time are practically limitless...

There have been so many dystopian movies about this kind of tech, it's a good insight of what comes next.