The Politics of Global Warming.... and beyond

Why is it, that every time someone brings up data aimed to show that our actions has had nothing/very little to do with global warming, the "main stream"-enviromentalists always point out that the data is just "manufactured" by big oil companies or other people who are politically or economically to gain from denouncing man-made global warming. Im not arguing that that isnt the case, but isn't it just a bit hypocritical?
If you take a look on the global warming-fanatics, they are predominantly people who have something to gain from it. How can it be that most left-of-centre people, the ones who are against free markets and "big bussiness" to begin with, are also dead sure what is causing global warming, even though they may have as much enviromental expertise as Paris Hilton. How come you never hear stuff like "of yeah, im all for regulating the markets and overtaxing big bussiness, but i dont think that global warming is really happening or that human action has had anything to do with it".
Why are the special interests of "the other side" never brought up in any main stream debates about global warming, when the special interest angle is always brought up when someone challenges the global warming gospel?

And this phenomenon isnt just occuring in the global warming debate. It happens in absolutely everything. Peoples personal preferences and feelings guide their political, economic, social etc. views in a manner that to me seems absolutely absurd. I mean, there arent many people who think gays are disgusting and wants to wommit when seeing two guys make out, who are at the same time strong advocates of gay rights. Just like you rarely hear of a person who likes to live an ascetic lifestyle without many material possessions, who is at the same time a strong advocate of capitalism and free markets. It is also quite rare to hear opponents of drugs call for the abolishment of the ban on drugs.

Why do people, even in this so called developed world, still feel like their personal preferences and values should have anything to do with what other people can or can't do with their own lives?