Any VW Group dealership that has the relevant marque business licences for their complete workshop system, can read all logged warranty repairs, servicing, workshop actions like updates and outside warranty repairs data - as can a proper VW Group Indie that has bought the same licences!
This "fixed miles/months" or "flexible" setting of the service warnings, is meant to according to the various marques, to set after having talked to the owner, ie how they will be using the car. High mileage users normally want the "flexible" service plan, low mileage user should be offered the fixed miles/months.
I've suggested above, I think, that all approved used cars get a quick oil and hopefully oil filter change before resell, and maybe that does not include resetting the service indicators if that would mean that that car would then overrun the miles/months that the remainder of the service tasks would be ignored before next worked on officially.