Why is New Jersey so disproportionately expensive?

I live right across the river in Philly and I get it, post 2020 rent and housing costs have gone up nationally. I'm not getting a 1 bedroom for 650 anymore. But you can still find sub 1k apartments all over Philly, in Delco, and some in Montco. I move the map over to Camden, and there is nothing. There is absolutely nothing. Scroll the Trulia map north, south, east, and there is still barely anything. When I search the entire map from Camden to Atco, there are 9 (non income restricted) listings under 1k on that entire swath of land. That's actually an improvement from the last time I looked.

Whether Camden is the next hot urban center or not is up for debate. But as of today, it's still very much the struggle. So why is it so expensive?