last fall I was eager to use it at my nearby airport...but the guy said "it isn't working today...it's broken all the time"
This summer I was going to use it at another airport and I read the signs and had my device in properly, it started to work but the lady said "no, flip it over and move it there..." and then nothing happened and with a LONG line and only one TSA agent checking IDs I just handed my license over.
My wife said, "I dont know why you are trying to use that. there aren't enough places that accept it anyway" ....and that's precisely the point, the more we try and can use it the more it becomes familiar to all around.