Why should a domestic manufacturer bother?
.380 is generally somewhat more expensive than 9mm, less widely available, and less powerful.
If I were going to buy a full sized pistol and the choice were between a 9mm and a .380, I'd choose the 9mm, and so would just about every shooter except for the original poster. There's really no demand and it wouldn't sell particularly well.
If the choice were between a compact 9mm and a subcompact .380, it's a little more interesting.
.380 is generally somewhat more expensive than 9mm, less widely available, and less powerful.
If I were going to buy a full sized pistol and the choice were between a 9mm and a .380, I'd choose the 9mm, and so would just about every shooter except for the original poster. There's really no demand and it wouldn't sell particularly well.
If the choice were between a compact 9mm and a subcompact .380, it's a little more interesting.