I have done some research on it, but I should do more.

Idk about a 'conspiracy,' but what I do think happens is that the critics of companies/industries overemphasize the sinister intent to the extent that it doesn't really capture how the business people involved actually thought about the situation. E.g. I was watching Supersize Me recently, and they were interviewing some industry lobbyist, who said that they wanted to provide more education about nutrition so that people could make better choices, but that their job as food suppliers was to offer the broadest range of food options possible. Now, that might have been sincere or that might have been a line to whitewash the practice of adding lots of sugar to foods to weigh them down with cheap filler that tastes good to uncritical consumers.

Anyway, with regard to GM, I think I could do research and find some accounts that are very harsh on GM as systematically attacking public transit and other accounts that say GM was just realizing a common-dream of personal automobiles for everyone because that was what people wanted and thought would make for a good future before they realized congestion and sprawl would turn into a nightmare.