Hey - I know exactly what you mean. When I looked at buying my Mk3 a few years back, some had plates riveted to the front, above the lights?.but none of the R platers did. I ended up buying an R plater with no VIN plate on the front cross member. It has a black sticker on the front wheel arch, and it is also embossed on the bulkhead at the bottom of the windscreen. Also, it can be found on various stickers round the car (including under the boot carpet, inside the door pillars).
My wife?s Polo (which we bought almost new from a dealer) is the same. Black sticker ONLY.
Lack of a VIN plate on a late Mk3 should not worry you I don?t think. I had my Golf checked by RAC before I bought and they ensured that the VIN plate was in correct location ? it was actually a box which they ticked (against which I could later sue them if it was false). I never verified it 100% but I concluded(having looked a loads of R platers) that the last Mk3s didn?t seem to have plates.
You could always call VW to check.