They don't (or should I say they didn't, as ID cards were cancelled by the subsequent administration). It's just another of Clarkson's hyperbolic rhetorical flourishes.how do they monitor pupil dilation and what for?
The world Clarkson writes about is not always the real world - it is his style to "make up" things like this, and new usages for old expressions as you have found in your reading and questions here. Many of these things you should not take "literally" but as "tongue-in-cheek" attempts at humour - his writings are to be enjoyed (and sometimes you need help with that, just like many native English eakers do) but not used as the basis to learn English.Then how it corellates with ID card? Is there eye-tests history coded?