It is because Big Brother - the Government, buys the information off the supermarket chains so that they can work out how much shoppers in general are spending on certain commoddities so that they, in turn, can raise taxes on certain items to milk us for all we are worth

That's nonsense, in the unlikely event of governments having that intention, it would be far easier to get the information from the supply chain rather than the sales side.

The info that comes from the cards is entirely for use by marketeers.