When I was there, I stayed one night on someone else's points, one night on my own points, and one night as a hotel guest. (Two different stays)
I was told by the CM that the policy was anybody staying on points would not be charged for parking. regardless of whether the person staying in the villa was a DVC member or not. So by this policy I would be charged the night I was a hotel guest even though I was a DVC member with my blue card, but not the nights I was staying on my own points or on someone else's (and they did not ask to see my DVC card that stay).
As it turns out, they did not charge me for parking the night I stayed as a hotel guest, but whether that was an oversight or a courtesy to me as a DVC member, I did not question.