"There are about 30 CVS stores in my city and about half the clerks insist on cash only to buy VRs. The other clerks take CCs. Go figure."

It happens because of pathetic training. Greendot Moneypak are cash only and they arrived long before VR, so older cashiers who were never trained that VRs can be bought with CC are PITA to deal with. That's why you get "cash only" barked at you by so many cashiers who "should" know better.