There are genuinely plenty of households which would struggle to save anything as they're around "break even" in their budget and could not strip out or increase income for different reasons. That might be the majority of people who are in this difficult situation in fact. However I have seen plenty of households which are likely cashflow positive with plenty of margin, but they are incredibly wasteful with money. It can range from eating far too many food deliveries - which can end up over quadruple the cost compare to making your own meals, to using Uber when they could walk a mile instead, to simply not managing their limited budgets in the most economical way or refusing to move down the cost of living scale, like buying from a cheaper supermarket. Some people create their own crappy situations and stick to them even if they're helped.
I've seen people earn more than I do (not boasting but to add a comparison), have less responsibilities, no rent, cars etc. and a generally "more affordable" lifestyle (in terms of responsibilities and goals), but yet, they barely have any money by the end of the month, I've seen both examples and I'm yet to understand how someone does it (I do, but why?).
In a personal level, I'm someone who travels a handful of times per year, and still manage to save some money. It's certainly not much, and if we were to add more responsibilities such as a kid in the equation, then I'm not quite sure on how I'd respond. Certainly, travelling would be greatly reduced, but still, the expenses are insane. If you do not have a secondary source of income, you're likely doomed into living from paycheck to paycheck.