Look at the kinds of projects apartments and leaky rural shacks the poor of the 50s-70s lived in. You might have to combine five to get what we today consider one working set of appliances and utilities.

Section 8 apartments and double wides are such a massive step up from that. There will always be a bottom of the economic latter. But that bottom has moved up a lot over the past couple generations.

Mobility is a somewhat separate topic from what standard of living constitutes the bottom.