That's true, but I would assert that if you gave two people a small cup and big cup, the one with the larger would still drink more, even with free refills. Mor

That's true, but I would assert that if you gave two people a small cup and big cup, the one with the larger would still drink more, even with free refills. More refills needed for the same amount if soda, more distance to walk, more time, etc.