It can't just be that they are assembled in Alabama. My research is saying Mercedes really dropped the ball on this class of vehicles.

Ah, but the toothbrush was invented in Alabama. Had it been invented in any other state, it would have been called the Teeth brush.

Isn't it possible that poor reliability and Alabama are synonymous?

This is just a question, not a slur to Alabama.

There were several years when Mercedes was associated with Chrysler and the quality dropped. They got rid of Chrysler and now they are back to normal. Even JD Powers (if you believe them...) admits that Mercedes quality is fine now.
There is a lot of people who just love to bash Mercedes for some reason. Maybe because they cannot afford one?... Do not listen to them. Mercedes is a great car.

If you want a true German car, it has to be built in Germany not America. I only buy Japanese cars that are built in Japan. There are differences in the quality and attention to detail than that of American built cars.