I can only speak from experience in the UK but if ATC pass you a RVR it will have been measured in some approved and authorised way. If there are no such approved procedures you will only be passed a prevailing visibility (i.e. what most people will call met vis). I would expect the same to be true in other countries.
Although these days ATC will often be involved in the derivation of met info at aerodromes, it's not actually an ATC function. Officially all (in almost every situation) ATC does is to pass on met reports that are produced by someone else.
As far as I am aware, aircraft ops procedures make a RVR - if there is one - the controlling element when deciding whether or not an approach can be started or continued. If there is no RVR then the aircraft crew can factor the reported met vis in accordance with Ops Manual procedures.