Cream soups wouldn’t, I don’t think. Others that I have in my pantry (vegetable beef, beef and barley, chicken gumbo) do contain sugar (sucrose, I presume), dextrose, and caramel. This could be because they contain tomatoes (in one form or another) as well.
You might be on to something with the tomatoes. I also just checked a can of Campbell’s Chicken Noodle soup, and that doesn’t have any sugary ingredient in there, either.
Heh. I actually have a batch of it in my cupboard. 
(I made it myself a few months ago. I forget for what, but it was in some Georgian recipe.)
ETA: Oh, as for the biscuits and gravy without gluten, the gravy is easy enough: use cornstarch or some other starch that is not wheat derived. The biscuits are going to be a bit rough, though. You can certainly make biscuit-like objects, but they’re not going to fool anyone.
I didn’t see this before I posted.
Quick breads aren’t inherently any more difficult than yeast breads, but any bread that needs to be soft but maintain an airy structure is going to be hard without gluten. Denser styles of bread or cake are not so bad, there are lots of grains available to combine to get an acceptable flavor and things like xanthan gum and eggs will give it enough structure to not be a brick.
As for gravy, it’s pretty normal to make gravy with cornstarch instead of flour. I always preferred flour flavor, especially for cream gravy, but gravy doesn’t need gluten, it just needs starch. I’ve found masa flour (made from corn treated with lime, like you use for corn tortillas or tamales) has a heartier flavor and better texture than cornstarch. For other gravies or sauces I’ve used tapioca starch which works similar to cornstarch but slightly less ‘slimy’.
I could go on but it’s getting off-topic.
Exactly why it’s unsatisfying. 
I fund a little protein in my food goes a long way to make it more satisfying. I gutted I can added why people like biscuits in gravy, but I’ll take a pass.
Hey, there’s a whole pound of pork* in my sausage gravy! And I drain off the fat! (Well, most of it, anyway.) :dubious:
*Weight before cooking. 