Its perception and supply and demand - in order to keep the union workers producing something and not just getting full pay for doing nothing, Ford and GM sell large numbers to fleets, which means a large supply of 1 year old vehicles.
That's why when you compare the depreciation curves on my 97 Taurus and 98 Camry, the Taurus drops off much faster the first year, but its curve flattens out quickly. Now the difference in value is $2k. The difference in purchase price was $4k (camry was more expensive). So the Taurus is ahead in cost there by $2k. Factor in repairs, and the Ford has cost $4k less, and it is the older vehicle.
Good example since my wife and I have a 99 Taurus. By the way it's our favorite car ever. Bad milage though. We picked the Taurus because of some of the very things you mention. There are a zillion of them on the road which gave us lot of choices. We ended up with a salvation title with the works for only 4000 bucks. It was a risk and so far it has been a really good gamble.
It's interesting to ponder resale value on camry vs Taurus vs Harley. There is a big value factor though. Harley stays valuable because of a lot of factors that are hard to translate to cars.