What you say makes sense but I"m gonna totally disagree based on "insider" knowledge. From both sides of the table. When I was at GM I was in Product Portfolio Planning. Much of the reason I was able to toss out the numbers I tossed out. I dealt with them all the time. I am also aware of how forward product planning and strategy development work and what needs to be true in order to make the type of strategy pronouncements GM was making. Part of the portfolio planning process involves ingesting and analyzing incredible amounts of external data to better "predict the future". We built scenarios in windows 5 - 15 years forward. Without doubt a direction locked in on Day 1 only approximately resembled the original strategy 10 years later but how close it came was dependent on the quality of the initial analysis as well as all the factors (regulation, material availability, new emerging technologies, competitor actions) but getting the "rudder direction" locked in has always been pretty important.
The common assumption that vehicle development takes 3 years from concept to car on the road is an over-simplification. Actuality is close to 5 - 8 years. The 3 year scenario is actually starting from the pot that the OEM has decided "we need a vehicle in this segment and it needs to fit in this square / segment and we need to capacities for xxx thousand per year in this price range and they will need to compete with A, B, C, and D". Those things are wrangled out in Strategic Planning and Product Portfolio planning before a single line is drawn to paper. When GM said in 2019 that they would be 100% zero emissions by 2035 they were factoring a full 2 product life cycles of gradually wind down ICE operations. That is super-aggressive. I didn't think it would be possible (they didn't ask me

) but I could see that it was aspirational (not hell or high water) and likely announced primarily to get the supply base to focus on it and take seriously the development of technologies to support.
One of the key sources for data, information, and market forecasts that we used when I was at GM was IHS Markit which was later acquired by S&P Global and recently (days ago) spun off as Mobility Global. They provided industry forecasts looking as much as 12 years forward on a detailed (Brand / Model / Powertrain spec) level. When I retired from GM I did some independent consulting, then hired on with IHS Markit just before they were acquired by S&P Global, so now I was on the other side of the table working with GM (and other OEMS and suppliers) on industry outlook and forecast.
I can say two things about the write-offs that the industry took on their directional shift from aggressive electrification plans. GM clearly was not the only automaker that was banking on a broad scale shift to EV. The fact that all these companies spent money getting their infrastructure, product development, and supply chain aligned is absolute proof that not only did they all expect the industry to make the shift, but also that they were intent on being within the leader group to get there. Why things shifted back is more a political discussion than an analysis of the markets and I'm choosing not to go there...for now. But I will say that if you look at the pace of electrification in all other key automotive markets and compare to the US, you would have to ask "what makes the US different?"
I retired from S&P Global just ahead of the recent spin off. And bought myself a really cool retirement present which is what brought me to this user forum.