Also, is there some sort of revenue generation happening here?
You can estimate it at about 30 Calories (kcal) per % ABV in a 12 oz beer. About 40 for a 16 oz (american pint), 50 for an imperial pint.
Basically, yeast converts a fairly predictable percentage (70%-80%) of the sugars into alcohol, so the Calorie difference between two different styles at the same ABV will tend to be small because they'll both have similar amounts of residual non-fermented sugar. (well, sours will often have a lot less residual sugar and particularly strong beers are likely to have more, so those estimates get further off for those).
Some beers do print the Original Gravity or Plato, and given that and either the final gravity/plato or the ABV you could calculate the amount of residual sugar for a much more precise answer.