I can understand the utility part of the argument.

But human beings have an innate drive for fairness in society. People will actually work against their self interest if they feel they are being treated unfairly.

The counterpoint is that the “small part of the problem” logic works both ways. If it’s such a small part, it shouldn’t matter if it gets taxed. Taxing would have little impact on the consumption dynamics while having a much larger impact on the perception of fairness

I disagree that caloric drinks like sugary soda (along with hyperpalatable food) are a small part of the problem.

From the standpoint of public health policy, it is a good idea to introduce simple measures that are effective for 90% of the target group. If it turns out necessary, you can find a (perhaps less optimal) solution for the other 10% later.

Obesity isn’t caused by excess sugar, it’s caused by excess calories. 6% is all sugary drinks, of which soda is a (major) subset. Taxing won’t eliminate consumption but it will reduce it. Say it’s wildly successful and soda consumption is reduced by 30%. If we’re being generous and say soda makes up 80% of the “sugary drink” category, the tax has reduced overall calories by less than 1.5%. I just don’t think that will move the needle of the country’s obesity epidemic. Will it have some impact? Sure, but I think our priorities should be focused on something that actually have a bigger effect. That small effect is what I mean by “feel-good” measures... they allow politicians to put a feather in their cap without having a meaningful impact.

Anecdotally I’ve known people who’ve lost a lot of weight by cutting out soda completely. But success at the individual level can’t be generalized to the population level. Healthcare is nearly 20% of US GDP and nobody doubts obesity is a real contributor. An outright ban on soda would be infinitely more successful and if that would solve the major problem of the industry, I think you’d hear more about it.

I’ll try to put a finer point on it. You can’t (shouldn’t) just increase the cost if access to alternatives is also part of the problem. If you don’t increase the access to high quality, affordable alternatives you will just make things worse. There’s a lot of discussion in this thread that is only looking at one part of the problem (consumption of unhealthy food) and ignoring the other aspects (like access to higher quality alternatives)