What about Healthcare?
We could link the ID card number to the Supermarket checkout, saving the need to issue a store loyalty card (less plastic hence more environmental friendly).
We could link the purchases of a family to their eating habits and send in a social worker if their profile shows they're not eating enough green vegetables, or drinking too much alcohol. What if they have a young baby and are not buying baby food? We should flag that too as a potential dead baby scenario.
We could then pre-emptively ensure their health for them, saving the NHS huge bills!
I know what you're thinking: "POLYCLINICS"!
Yes, of course, Polyclinics! if the doctor says you need to stop smoking, we can link the purchasing record to the ID card and the supermarket record to the ID card, and flag anyone who is not obeying the doctor.
Why advertise on TV telling people to eat better, when we can monitor them and intervene directly! Why limit the use of ID cards to just security, taxation, airport ID, proof of age at off-licenses, and police random searches, why not let our caring, snuggly government gently target people who need assistance, and we can send round the appropriate authority to tackle it.
But why stop there, lets generalize it so that any authority figure could set any condition in the database and our caring computers, or 'caruters' as they henceforth will be known, will ensure that whatever rule is required by the authority figure is complied with.
For example, an officer has decided that you cannot enter the center of town after dark, using their new Labour Anti-Social control orders. But what if they then go and purchase alcohol in an off license in the center of town???? What then? Their ID card age verification, will be flagged in our database and we can ensure such anti-social behaviour is not tolerate!
The possibilities are endless, together we can make Britain into a perfect utopia!