I know the stores around here will card everyone in the group for alcohol. In fact once we were at the grocery store and buying a six pack, they carded me and then asked for Partner's ID and she didn't have it with her, they wouldn't sell it to us. Even though we are both over 21. She went out to the car and I came back in and bought it by myself. Never experienced it with cigarettes but I can see why they'd card. I'd buy them for my grandma once I turned 18 and always got carded.
Heck sometimes I still get carded going to see a rated R movie. I'm 27. I don't think I look under 17, but it takes me two seconds to flash my ID and hey if I look 10 years younger I'm cool with that. Oh, when I was under 17 we went to see a rated R movie and our over 17 friend went to buy the tickets, they wanted to card all of us in the group because she was clearly not our parent or guardian (our parents and guardians knew where were and what we were seeing and didn't care, it was American Pie 3, we'd already seen the first two). We just stood off to the side and she said her friends hadn't arrived yet, they sold her the tickets but told her next time they wouldn't.