With Sally's it seems to depend on the branch as to who they will sell to and if they want proof of who you are.
I've misplaced my trade card so have to order a new one. On a few occasions I've given my name and postcode and have bought items easily without being asked for anything else. However the last time I went to a branch in Glasgow which I don't usually buy much from, I was asked for the usual info but was then asked if I had any proof of ID. I was delighted to be asked as it meant they were actually checking who they were selling too. I have a 'friend' who likes the idea of me having a Sally's trade card and knows my name, address etc. I know that she has used this once in the past and would love it if she were caught out at the till
This particular Sally's store also refused to sell something to the 2 girls in front if me as they were not professionals. Not sure what they were trying to purchase. I hope other Sally's stores will be putting these restrictions in place.