Piggy in the middle

I have a middle name. Yep, a splendid little fellow, going by the name of J****.

So that makes me Anglo J**** Saxy. And this full name is printed out on all sorts of IDs - such as my credit card, my health card, my ID card.

But why do people in this country, when confronted with one of these items, insist on calling me J****? If they called me Anglo or Saxy, I'd understand, but J****? They just can't get their heads around this middle name concept, eh?