He says it in the article but it walkways bears repeating: if you aren't the customer, you're the product.
I assume they can still track your purchases by credit card #.
I'm several decades past 21. There's no way in hell that I'm an underage drinker. When pressed the last time I was there, I was told that age verification up to the age of 50 is store policy.
In bars occasionally young women will come in who will give you free packs of cigarettes in exchange for scanning your ID. I've heard, mind you, this could be completely false, the cigarette companies sell that data to insurance companies.