This was about households rather than individuals and housing units instead of homes, and privacy is unrelated to the discussion. For example, longhouses typically had internal subdivisions that functioned as housing units. A household that cannot afford a baseline housing unit is unusually poor, regardless of its size.
In a developed country, the baseline housing unit most households can afford is typically an apartment or a house. Households that cannot afford one are unusually poor.
Someone who forms a single-person household and doesn't earn enough to rent an apartment is poor.
Single-person households are often poor, especially when the person is young. Living wage estimates for such households tend to be higher relative to typical wages than for larger households, as the idea of a living wage is largely about rising above poverty.