NOx led to the VW emissions scandal, so we take the quite serious. CO2, well, we should be more aggressive, but it is tackled, e,g, no new ICE cars in the EU after 2035 (?). I still remember dead forests due to acid rain, caused by various sulfur-based shit in the atmosphere, we got rid of that. Same for some of the ozone layer destroyers, we got rid of those, too. That it takes longer to get rid of that crap shouldn't be used to accept start-ups intentionally (as opposed to being a side effect like other industries) polluting, and promoting that, as PR stunts and funding vehicles. Especially since the latter can be so easily stopped.

Well there's breathing, is that not normal?

Presumably there exist multiple organism that live in a balance, some emitting CO2 and other absorbing it. Being a productive member of an ecosystem is fine, but flooding that ecosystem with excessive emissions is not.