I'm more confused by how this seems to be a recent phenomenon. A decade ago non-trucks and light trucks were on roughly even footing, but after about 2015 the distribution shifts meaningfully towards light trucks. What made Americans want trucks more?
"Light truck" is a problematic term in the US -- it can be defined in multiple ways, often exacerbated by automakers desire to get around fuel economy requirements.
Assuming that "light truck" in this context includes SUVs, that may correlated with the introduction of sub-compact SUVs into the US which have been extremely popular with drivers who are intimidated by driving large vehicles and like the confidence of sitting higher than in a traditional car. Many of these are basically just hatchbacks with some stying tweaks a couple inches of extra height.
So it may not necessarily be "Americans wanting trucks" that you're seeing in that data, but instead "Automakers styling their vehicles slightly differently, calling it an SUV, and avoiding fines for violating CAFE standards"
Some of it is supply: the manufacturers build more and the dealers find ways to sell them. Those marketing efforts drive what average people "want". (That's the role of marketing.)
Some of it is a brinksmanship snowball: If I'm safer in a bigger vehicle when more other people are driving bigger vehicles, I need a bigger vehicle.
Some of is budgets: There are a lot of sub-factors here, but one key viewpoint is that there are two very strong markets with very different goals. The new buyer is looking at marketing, and swayed by fashion trends, on average more likely to trade in for the "newest model" for aesthetic or fashion reasons on a regular basis. The used buyer is more budget/maintenance driven, more likely to use a car for utilitarian purposes than treat it as a fashion symbol, more likely to drive the car for longer. Car companies are selling to that first buyer and what they (think) they want, they don't care about the used car market because they don't get their cut of the used car market. There are arguably a lot more used buyers and car companies don't care what they want. To some extent they take what they can get after the "fashionistas" get bored and don't express their wants all that directly.
Some of it is maintenance: The average maintenance life for sedans still seems to be much higher than trucks/SUVs. Longer maintenance life is longer life in the used markets and longer life on the road. It's anecdotal data, but have you ever car watched and tried to estimate the average model year of the cars that pass you by? To me SUVs and Trucks almost always look at most five years old, but you'll see all sorts of 10, 15, 20 year old sedans.
I think those last two points are especially important asterisk to that "Americans don't buy sedans" from the anecdotal perspective of what you see on the road: Americans don't buy new sedans regularly. Sedans seem to last 20 years on "average". Sedans are rarely "fashionable". Sedan buyers favor good long maintenance life. It was the "lesson" of the 80s wave when Japanese manufacturers proved Americans were desperate for reliable, easily maintained sedans and compacts. It was again the "lesson" of the late 00s wave when Korean manufacturers proved Americans were desperate for reliable, easily maintained sedans and compacts. It seems like a "lesson" doomed to repeat roughly every 20 years as old ones age out of the used market. (I think the current EV manufacturers are ignoring/forgetting the "lesson" at their own peril. It could be someone new and fresh like the Chinese this time taking advantage of the used market's huge desire for reliable, easily maintained EV sedans and compacts.)
Right! But the quote you responded to was, "Americans just do not buy sedans". In the context of that quote, it appears that you were using your anecdotal observations to suggest that Americans do buy more sedans than trucks.
https://www.edmunds.com/most-popular-cars/