I like privacy. What I do with my money is nobody's business.
With a very few exception, I don't trust anyone, and the State is the entity I trust the least. Historically the worse atrocities have not been committed by individuals, but by governments, and the fact that the government would want to track everything I do is a scare proposition.
Polish extermination? Government.
Cossaks extermination? Government.
Jew extermination? Government.
Holodomor? Government.
Armenian genocide? Government.
Ah! But those are things of the past!
Uyghur genocide. Ongoing, government.
Rohingya genocide. Ongoing, government.
Darfur genocide. Ongoing, government.
Governments that want to abuse their population first remove their ability to defend themselves, queue gun control and removal, then remove their ability to store wealth, so they take the gold.
Now, I am confident that you have absolute trust in the British government, all parties have solid proven records of trustworthyness and we should give them all our details knowing that are in safe hands, who would not trust our Tory government or a possible Labour government with all of out private information? You know, the guys that keep repeating that we need a wealth tax.
But bare with me for a minute, say that by chance someone not trustworthy takes over, or maybe we are invaded by a foreign entity or, without going to excesses, the government gets hacked, or someone steals and sell that data, and now you have a bad actor that knows exactly what and where you have it, would you not have wanted to keep that data private? And what better way to keep that data private than to use cash?