Unlike the USB-C Expansion Card, I wasn’t able to open the USB-A cards (following this guide).
That got me thinking about why it could be metal. The first thing that came to mind was that it had to be conductive and that some wire on the inside is soldered to it, and that could also have been the reason that I couldn’t get it open. However, nothing conductive in the Framework Laptop seems to make definite contact with the metal plate. The metal plate does make some contact with the outer metal housing, and the outer metal housing might make contact with the metal body of the laptop, but the contact isn’t amazing so I highly doubt it’s designed for this.
That’s a very good point. I was able to slide the metal cover of the USB-A card back a little, like a millimeter or two, and it looked like components were right up against it, or at least almost, unlike with the USB-C card where there was a lot more room.
I can’t find the post, but I do remember there was a post from the devs saying it was because of the size of the USB-A socket meant that the expansion card cover had to be super thin, too thin for plastic