If I understand correctly, fingerprints were quite the nerdy technology back then. They're not beep boops in a data center, but it takes a high degree of nuance to argue against "if you didn't commit a crime, you have nothing to worry about."
Neither does this specific "nerd". I honestly have yet to be convinced; a lot of it seems very similar to fear mongering and illogical with the arguments being very nebulous. Maybe I have yet to sit down and flesh it out with a deep privacy advocate.
I understand the need for wire tapping and for the police to be able to do their job. What I don't understand is the no need for a warrant. Also the list of public bodies who can access this data includes the health and safety executive, the pensions regulator, the environment agency.
I see no reason why bodies like this can have access to sensitive data about individuals without requiring a warrant.
Not that long ago the most powerful and free country in the world was engulfed in chaos after the killing of George Floyd.
The event was polarising and you had your anti-rioter camp and anti-police camp. It should not be hard to see how there would have been direct chains of command on either side which could facilitate data misuse.
If you want a hard example, look at Hong Kong: protestors getting arrested via all manner of tracking, but also police's family being doxxed by protestors.
The big problem is that our modern legal code is so convoluted that people regularly accidentally commit crimes[0][1] but aren't aware of it, leaving a big gap for inconsistent enforcement (mostly against those who dare challenge authority or the authorities are biased against). There's reasonable evidence that the FBI or rogue agents within the FBI tried blackmailing Dr. Martin Luther King, Jr. into committing suicide.[2] J. Edgar Hoover was collecting a stash of blackmail information on politicians.
I'm very unlikely speak up enough to become a target, but the next Dr. King, the next Snowden, the opponents of the next Trump or next J. Edgar Hoover are going to have big problems if privacy continues on its present course.
Privacy isn't currently a big problem for the average citizen in our society, but it's very important fat-tail event insurance to have in the future. By the time you realize you need to worry about privacy, it's probably already too late. History has shown liberal democracies are at best metastable (all governments tending toward authoritarianism if not actively maintained) and whistleblowers are an important stabilizing force.