Are all states' drivers licenses the same or similar?

I work in a drug store where we ironically sell cigarettes. A kid came in yesterday with a Maine drivers license and wanted to buy cigarettes, this is Pennsylvania by the way. But the ID was blue and seemed old and didnt have a strip on the back that we scan through the credit/debit key pad so the computer cant calculate his age. This whole situation got me thinking, should i accept other states drivers licenses if they look different and dont scan?