The "bedroom community built on inexpensive rural land some distance outside of city boundaries" in my area was actually connected to the city by electric railway lines (whose right-of-ways still largely exist, as bike paths). This was before the big mid-century paradigm that GP describes, which absolutely was a(n open) conspiracy to create racially-segregated communities. There were a lot of amenities that these communities went out of their way to fund, so expense was a concern only inasmuch as the money that would have gone to sidewalks instead went to a community pool or bike paths or water/trash services.