John Gapper worries that taxing non-diet sodas would be regressive. I worry that it wouldn’t even do what it is designed to do, which is reduce obesity: all it would do is increase the amount of diet sodas consumed, and there’s a strong link between diet-soda consumption and increased obesity.
Unless and until there’s some empirical evidence that switching from non-diet to diet sodas helps people lose weight, this should be filed under "very bad ideas".