Because a car is required to live in the US outside of a select few urban areas, and recycling essentially doesn't exist. The cognitive dissonance is real, but practical reality is a bigger factor than hypocrisy IMO. There's also the bit where much of North America stands to benefit from warming, but I doubt such long term thinking factors in much. Then we have the disproportionate impact of industry which makes individual sacrifice relatively ineffectual. The most effected by climate change are generally relatively small populations in relatively poor countries, not likely to get much sympathy from the rich west.