Sure, but drywall/plaster and paint are a tiny tiny fraction of the cost of a house.
Taller walls tend to come with taller windows. Not just more glass... sometimes whole extra windows (transoms) which cost almost as much as the much larger ones below. Taller cabinets or soffit details to receive them. More elaborate trim work. etc.
For a flipper or a production builder every dollar is saved because it adds up in the end. If there's a high ceiling it's because it's been determined to command a good profit.
Over here, the standard room height is 2400 mm or 2500 mm, and my house has 2780 mm. I'm happy with the extra overhead space, but there are all sorts of little things. The drywall boards actually had to be ordered separately, and the price increase is not linear. They're heavier to carry - again, not linear - so installing is more difficult. Working on the top parts needs higher scaffolding. To get to the attic, I have this factory-made foldable ladder that opens from a hatch in the ceiling and then folds out with three hinges; it's factory-made for 2500 mm room height so I had to add a 35cm piece to the bottom with another hinge so that it would reach down to the floor and be steady.