Not sure what poor or lower-middle class communities you've lived in, but where I grew up, kids who were insecure about being clearly being disadvantaged by society's standards made a pretty big deal about the little they did have, and readily lorded it over those who didn't. If you all lived in the same shitty apartment complex but one kid had a nice pair of kicks, it was pretty noticeable. Beyond that, the only other people in poorer communities visibly living in vans are probably severe addicts and other folks not willing to or capable of living their lives in closer step with most other folks. Those are some pretty tough social stigmas to overcome.