The first time it happened to me, I was flattered. The second time, it irritated me. I had seen the place get busted for selling to minors the month before so I wouldn't doubt that had something to do with the carding.
Maybe they have to go on some kind of probation and implement the carding of everyone to keep their liquor license. I still would feel uncomfortable having my license scanned. I wouldn't care too much about them just checking my license to verify my age. Even if it is rather silly.
Then there is the thought that maybe I don't want to support a place that sells to minors to begin with.