The meeting had many residents virulently opposed to fluoridation, I've talked to quite a few of them, and they're as fervent about their cause as many other people are about the science and medical causes they fight. What's different about this fight they have against the scientific establishment is how easily mainstream science can overcome their strong opposition in the political arena. Most Americans drink fluoridated water.
So why does it work for fluoride and not so easily for climate? One answer is the simple establishment message: fluoride is effective, and fluoride is safe. The first part of that message is accurate. The second part is pushing it some - more accurate would be "fluoride is effective, and fluoride's risk is at most small, mainly to certain small subsets of the population, and outweighed by the benefits of fluoride." The establishment doesn't want to say that, except when I pushed them on it. But their simple message works (except for me).
The other answer for fluoride was apparent from looking out at the audience - there weren't any powerful allies for the fluoridation opponents, while the representatives of the health establishment made their preferences clear. The ability to change from no fluoride to fluoridation becomes clearer in the absence of a powerful opponent.
It's similar to the issue Old Eli discusses, ozone depletion. The scientific establishment could've faced powerful industry opposition to phasing out CFC's, but instead it faced Dupont, the early popularizer of the chemicals. Dupont toyed with science denialism for a few years but then backed reality. This probably had less to do with ethics and more to do with expired patents and new competition to produce CFCs while Dupont had a competitive advantage in the replacement chemicals. Had Dupont decided differently, then I think American and the Reagan/Bush Administrations wouldn't have provided the global leadership that they did.
Dupont's counterpart in the climate context is Exxon (and some others), and the behavior difference helps clarify the different political outcome from ozone depletion. It's not the fault of the scientists, maybe only secondarily of journalists. Politicians will have to face their own consciences and whatever theological construct holds true in the end, if any. But I think the primary message is corporate power, especially when playing defense, can hold on for a long, long time.
Teaching evolution is another test of this idea. Basically, the scientific establishment wins from college and up, while only a vague form of evolution is vaguely taught at lower levels of schooling. No corporate power has fought off the scientific establishment in high schools, so I'd agree that the principle isn't that corporate power explains all US politics. Religious beliefs tied closely to conservative political affiliations are an independent power source to fight science in that case, so every situation can be a little different.
One last thought on fluoride - it used to be a politicized issue, with the hard right wing in opposition. That's gone away, so it is possible to depoliticize a science policy issue.
UPDATE: worth noting that Ted Parsons wouldn't agree that Dupont had an easy out. Still, Dupont reacted very differently than the fossil fuel industry to its crisis, both in the politics and the speed at which it shifted its own business model to using substitutes.