They do, and if you shop carefully (and in bulk) you can save some money. Unfortunately, no deals on this for Prime Day.

Apparently Nuun has changed the formulation recently, which is maybe why I was able to score boxes of 8 tubes for around $30 each a few months back. To my palate, the Tri-Berry I normally use is more tangy.

I'm not a chemist but I believe the Nuun tabs acidify the water slightly, making it much more thirst-quenching, at least for me. I've read all the Osmo/Skratch Labs PR, and while I don't doubt it, personally I dislike sugary stuff when riding. Nuun tabs fit the bill nicely: electrolytes, plus flavoring, and no sugar. I drink a lot more when using these tabs, no question, in comparison to straight-up water.

As an aside, I use them in my Camelbak bladder when riding dirt, and I can clean it by simply rinsing it out. I'm pretty sure that something sugary would leave a residue and would require more extensive cleaning.