Mostly the value in tracking you comes from profiling you, i.e. building relationships between facts, mostly metadata about what you do over time. But biometrics aren't metadata and aren't what you do.
I did mention "discrimination" but redacting data in case future governments are racist isn't all that useful; they're the government, you can't hide from them, and since discrimination isn't based on real objective categories then you can't predict what it will be based on. There's no biometric for being a Cagot.