Not Quite Alcohol-Free: A Mystery

The picture below is of a “beer” I drank at a friend’s house this past weekend.  It actually tasted pretty good; but why 0.5 percent alcohol, which surely added to the cost of production, but couldn’t, I think, have added to the taste? Including the minuscule amount of alcohol would certainly exclude teetotalers from consumption; and to get any kind of buzz a real beer drinker would need to drink at least several gallons.

My only explanations are: 1) Having a little bit of alcohol somehow deludes beer-lovers into thinking they are getting something approximating the real thing; or 2) Some tax deal made it cost-decreasing to include a bit of alcohol, although I can’t see how.  Any others?