The trouble with asking what the data will be used for is that the uses proposed are probably harmless enough, so everyone gets happy with the system and then less ethical uses get sneaked in later.

You can also bet that "privacy" would be advanced as a way to decline any requested use of the data that might be helpful to the individual, such as providing an alibi. On the whole, you largely have to accept that your life is no longer your own.

I haven't had Fred's experience with a metal turnstile gate, but a glass revolving door with a similar mechanism was the bane of my life (and that of around 2000 colleagues' lives) at one call-centre I had the debatable pleasure of inhabiting.

Around 10 years ago at a supermarket with an electric-eye-operated sliding door I had the joy of it closing on me as I passed through. The door in question is about 7'6" high by 10' wide and closed with enough force to trap me momentarily. Luckily at about 170.lbs I was solid enough to just get a slight bruise to my shoulder. The staff apologised, but seemed unconcerned when I pointed out that while a healthy chap of 40 odd years could take the blow with just a bit of dignity lost, an old lady of half my weight would be lucky to end up in hospital after such an impact. I left it to the queue outside to point out that the collision had derailed the door, and that it was no longer admitting customers.