@AC Re: Loyalty cards
1) I choose to give these people my data when I choose to present my loyalty card at the till. On a visit by visit basis. Care.data is opt out so you're in by default and you don't get to choose who gets what data about you.
2) I am incentivised by the loyalty card company to give them my data with money off stuff and special offers on things I buy normally. In return the big supermarket chain might sell me more cheese and beer. With the care.data scheme I am not incentivised, the data recipients get all the benefit.
3) Loyalty card schemes are not set up at taxpayers expense to benefit private companies.
In fact I was unsure how I felt about the care.data scheme until you came up with that marvellous false equivalence and I had to think about it.