Lets put that theory to the test, lets imagine a world where each transaction is added to companies and private citizens total tax record, and then all details are imminently deleted. At the end of the day, you get the same total sums as if you had all the individual transactions, but you can't derive any additional information. Would this be an acceptable deal for introducing a cashless society? My conclusions is that the banks would not accept it, and the government would not accept it. By default, cash would thus continue.
Banks would not accept this deal, as they need the customer data for data analyzes and market research. It is also a resource to be sold in some places or to be "shared" by "partners" like insurance companies and marketing firms.
Government would not accept it, since if the tax department get this then a dozen other department also want it. Police, secret police, and prosecutors want to dig for dirt, and has a long history of ignoring anything that would benefit a defense. Social security want to dig through it in order to skip doing a real assessment of a person (having dept is a good sign, and a buffer is a sign that the person should be denied help). Political parties and political research wants to analyze it and draw conclusions without having to talk to people and do polls.
I do not want someone else to analyze my transaction, and if they have to, I want safeguards that prevent incorrect conclusions to be drawn. As it stand, there isn't any, and its barely even recognized that I am a stake holder with any rights over the data.