It's about jobs and profits. Many seem to think, right or wrong, that trying to impose much stricter regulations would cost hundreds of billions and will only end up in rising costs, lost jobs, decreased profits and pushing the remaining manufacturing to China, India and whoever else can build it cheaper and without much regard for environment. Also there's no consensus among scientists on what needs be done (nobody except a few nut cases really doubts that the climate is changing, the question is what's driving it and what can be done about it). So, without forcing the major developing countries like China, India, Brazil to adapt the same stringent standards, the push to curb emissions in the US will only lead to the implosion of US manufacturing without much real impact on the problem itself. And good luck trying to force China to stop polluting.
Unfortunately, there's really not much worldwide political will to fix this - a lot of push comes from countries that had already heavily invested in green technologies, for other reasons (many Western European countries) or countries that gave up their manufacturing long ago.
Put it this way - Germany is all for more stringent worldwide environmental regulations, it also happened to have some of the greenest manufacturing in the world. So not only it is doing the morally right thing, but it is also posed to rip the benefits by becoming more competitive overnight if the Kyoto is ratified and made into international law (they already spent the money, but US would need to spend mucho $$$ to catch up). But China needs to spend $$$$$$$$$ and it's not going to. So Germany is all for this, US is resisting this, China pays lip service to this issue while it continues poisoning it's own air and land and water (although they are starting to push it outside of major metro areas, as people in Shanghai are now wealthy enough, make money in sales, management and finance, and don't want to live with the smog anymore - they would rather let the provinces breathe it.).