I didn't downvote them, but I am genuinely curious to hear from people who "can't save money", and try to understand why that's the case. My assumption is that a large percent of them are spending way more than they need to, but that could easily be an incorrect stereotype.

Federal Reserve studies indicate that 10-15% of the US population can’t save money due to fundamental financial realities. That is, the necessary expenses of an ordinary lifestyle consumes all of their income. That is tens of millions of people.

There is another ~30% that expand their lifestyle to consume all available income. Not saving is a choice for this part of the population.

It's actually almost certainly true just on the basis of basic numbers. Many people who are really actually quite poor (making say under $35k CAD annually for a family of 5) manage to make ends meet and even save a little. So if you make more than this but can't save any it's because you're spending on things they are not and which are therefore nonessential.

Now maybe restaurant food, name brand groceries, driving two SUVs, vacations, etc etc whatever it is for a given person are seen as essential. That's how lifestyle works after all and we often can't imagine our lives without it. So I'm not saying it's a "simple" matter of just spend less because it's often not very simple feeling. But from a numbers PoV it is possible for most people who otherwise see themselves as struggling in theory.

Are you excluding all the people with disabilities or chronic illnesses or supporting children or parents or other dependents with disabilities?

No offense, but: you need to get out of the house more. It'll answer your question very quickly.