Consider the perspective that those corporations are almost uniformly dedicated to providing goods and services for citizens to consume, with a few outliers. The parts that nominally aren't are generally part of the control structures that anticipate what people are going to want to consume in the future and make it available.
Corporations producing less emissions is equivalent to consumers consuming less.
This depends... there are whole subreddits (eg: https://old.reddit.com/r/NonFunctionSlackFill/top/?sort=top&... ) dedicated just to slack filled items, to make them look bigger (thus increasing the amount of packaging and waste, and increasing transportation emisions).
Right, but filling that slack fill would consume the same amount of volume, and more mass. So filling in the slack fill is strictly worse for transportation emissions. And crucially, the manufacturer would have to produce more of the actual product which in turn means more emissions from raw materials and refining those materials into goods.
I think, in a way, that subreddit really reinforces what the parent comment is saying: people don't like it when their consumption decreases. When we see this [1] our thought isn't "how great it is that the company didn't spend emissions on building a full set of crayons", it's "this sucks, I didn't get a full set of crayons".
Corporations producing less emissions is equivalent to consumers consuming less.