I have a 2003 and it doesn't have them. I "think" they can be retro-fitted, I looked into it briefly last year. Main dealer wanted in the region of £40 a pair (ie one seat) and from memory they screw into a captured bolt in the floorpan. Not done it myself yet, but will be soon.
As the vagcat diagram shows, two lumps of metal and 4 bolts for the rear. Really not a big job!
I can see their point about the fronts, the airbag must be disabled if your fitting a child seat, so without the switch it would be unsafe to install the isofix mountings. Surely the rear is sufficient though?