Why does my Dominick's have TAB but not Vernors

I was all set for a Vernor's float tonight, but no Vernors at my grocery store! So I made root beer instead. I was hungry enough that I had it for an appetizer while my chicken roasted, rather than dessert. Delicious. Also, I am especially pleased that I did not eat the entire pint of Ben and Jerry's I bought to make it. I've got a problem with ice cream in the house.