Also, loyalty cards (eg Nectar cards) already share the information with HMRC to cross reference your spending with your income tax to determine if you are spending more than you earn; Which therefore indicates that you are not declaring your full income and should be paying more income tax.
Bruce Wayne - can you evidence this?
I find this particularly worrying. Regardless of HMRC being so incompetent as to probably find no time to use the information, the mere access that they have to it is not, in my view, something I signed up to, if true...