This forum proves I am not crazy. I thought it was just me.
I needed a new car two years ago. I looked for used cars, and realized that 99.5% of them are sold through dealers, at least here in Canada. I later figured out that the reason is that dealers can offer financing, and that most people who sell slightly used cars trade them in. Private sales for lightly used cars are very hard to find. And of the "private sellers", half are curbsiders and a quarter have very unrealistic pricing expectations. That narrows the field further.
I also did the math on a whole bunch of used cars, and almost universally they would be 4 years old, 30% off the new price, with around 70,000 km on the odometer. For me, that represents six years of driving. Mentally, I fully depreciate a car over 10 years. So paying 70% of the new price for a four-year old car makes no sense.
In the end, I ended up buying new.
Maybe in the U.S., there are more private sales and the math is different.