Let's look at another positive, what if some poor people end up saving money because they don't want to spend anymore on soda?
So the benefits are twofold: A healthier life and potentially more money in the pocket.
Evidence and past experience hasn't bore this out though. Poor people still end up buying the item, so they end up spending more on soda.
Sin taxes can be justifiable when they 1:1 go along with a campaign of education against the sin. This is almost never the case, the tax is used partially for educating against the sin, and mostly towards something else.
Sin taxes also have to be a delicate balance, or else cities
lose revenue on them, especially if they risk running education campaigns against the sin.
In New York City, 60% of cigarette sales are illegal and free of NYC's steep tax on cigarettes. The city ends up losing money on the sin tax and at least in the last half decade, smoking rates have
increased in the city.
If there's a sugary soda tax, why should coffee ( other than plain black coffee ) be exempt?
These need to be taxed if sugar sodas are. Lets not discriminate
I'd imagine almost all cities implementing sugar taxes would also be taxing highly sugared drinks like this. "Soda taxes" are nicknamed "soda taxes" but they're applied to any highly sugar'ed drink like in the OP, his example was Sunny Delight, an orange-juice like substance. *Edit* Although, there may be exceptions for drinks made on the premises... For instance, beer and wine is taxed as alcohol if you buy a 6 pack or a bottle retail, but if you go to a bar and have a pint or a cocktail, it's taxed under the restaurant/hospitality tax usually. Hospitality taxes are almost universally higher than sales taxes so it hasn't been brought up.
That said, taxing coffee with simply cream or milk ("anything other than plain black coffee") is ridiculous. Do you really want to implement a
milk tax?