Discounts for DVC Members on Ancillary Items

[stlrod]

Can somebody please explain to me why guests and DVC members paying cash do not get the same discounts as DVC members staying on points. For example, when we stayed at VB last week, the cost of a craft was $7 for a member and $10 for a non-member. Does dues cover a portion such that a discount is warranted? (I'd be surprised if this is the cases.) Is Disney actually giving the DVC member a discount off their cost? (I doubt this one too.) Or is this simply a marketing ploy to get guests thinking of purchasing to cross that line?