Correct most likely, unfortunately
I gotta admit I failed to see the benefit here.
A future buyer would pay more for a finished basement, regardless if it was included in the listed square footage of the home or not. That's taken into account when you're looking at comps. A future buyer would also pay less for a similarly sized property that has more square footage listed due to the higher tax bill.
This means at the end of the day adding the square footage to the home has, at best, no effect at all but in real terms it means higher tax bills and possibility a lower final sale price when you sell the home.
The only logical reason I can see for this is if the town you live in requires it and it was unavoidable.