A lot of homeless in America are people who had a decent paying job and lost it. So, they had some material wealth before becoming homeless and this could have included a car. At that point, people may prioritize the car because it provides transportation and shelter while the home only provides shelter. It is also likely that the car is cheaper than an apartment.

There are also a growing class of people who live out of their car and migrate across country during the year. A lot of these people are retired or have some disability insurance, want to travel, and see being alone on BLM land as preferable to living in a dying rust belt town.