Another reason is that soft drink bottlers in the US don't claim that they're using "natural" spring water when they're just using municipal water supplies. That lack of deception might explain some of the difference.
Finally, some of the bottled water hatred is specifically focused on Fiji water. Soft drinks tend to be bottled locally whereas Fiji water is shipped to the US from an island in the Pacific controlled by a dictatorial regime. The idea of shipping water across the planet because idiots are easily seduced by a glossy marketing campaign rankles some.
Coca-cola tried that municipal/tap water scam in the UK, but ended up having their product pulled from the shelves because it was contaminated with bromate. After that happened, they completely pulled the brand from the UK.
There's the other side of the local argument. Soft drink manufacturers tend to source the water locally, so you get reports of bottling plants competing with local farmers by draining water from aquifers in poor countries.
Anyway, I agree with all you have said, but I still think soft drinks are the worse of the two. They screw up peoples' health.
I think we totally agree.