In the 1930s, the Netherlands kept detailed records of ethnicity for every citizen. No one thought this was unnecessary, as ethnicity wasn’t something that could ever be used against you.
That line of thought ended when the Germans took over in may 1940. Unfortunately those records still existed, and aided the most efficient genocide in human history. Without those records, many jews, sinti and Roma would’ve been able to deny their ancestry and evade being murdered.
Privacy from government and corporations will one day save lives.