They're built on a production line so doubtful it's a factory error, more likely a cost cutting repair
I've seen a lot of VW's with very bizzare combinations of specs in my time *, so I would never rule out factory error, but I agree that cost cutting (or simply ignorant) repair is the most likely reason for the lights being wrong.
* For example, my fiance's mk4 has half of the front seats with heating elements (drivers seat back and passenger seat bottom)
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with no seat heating and there has definately never been any seat repairs or replacements on the car