The lowest bidder. They're probably made all over depending on what car or truck it is for.
Ford probably have some no name front company making them. I found that a lot of the branded products we get come from the same never heard of them factory. Like oil fliters and batteries. I am sure shocks are the same. Find who the largest shock maker is. Also look to see where the shock was made. Probably Mexico or South America. I got some Motorcraft shocks once, and they were made in Venezuela. I had some Gabirels, and they came from Venezuela. They were the same shade of black. Looked like the same everything. I am sure that factory makes other brands.
My parents company back in the '80s made the struts and shocks for the Taurus and a few of the heavy duty trucks. We low bid so it could be anyone. these days it won't be the mom and pops because the jobs pay nothing and the auto makers tell you what your profit will be so they tell you what they will pay. Auto contracts we stay away from because quality is to last till the warranty on the part has expired.
I know Motorcraft oil filters are actually Purolator, and they are one of the more expensive designs they offer. The Motorcraft is actually cheaper in price than what it should be. I always buy the Motorcraft. Also, Motorcraft spark plugs are made by Autolite. I'm not sure about shocks or anything on our cars, but I swear some of the newer F150s' rear shocks look like they might be Bilsteins to me, from being yellow and blue.