Rail works just fine in the suburbs of Sydney, Australia. It's not great, but it's still cheaper than cars.
Besides, if you care about costs then suburbs/exurbs are fundamentally uneconomical in general - most of the cost of housing comes from the land, of which suburbs are fundamentally wasteful. Literally everything there is (relatively) uneconomical, and is only widespread because the alternative is literally illegal.
Most of the cost of housing absolutely does not come from land except in massively overpopulated cesspits. Proof: a 1600 sq foot single family home on an acre of land is going for approximately $350k here currently. At current land valuation $30k of that is the lot. I live 15 minutes away from one of Apple's satellite offices so we aren't talking a ghost town in Nevada either. Cities suck, as does the expectation that everyone crowd into one.
Besides, if you care about costs then suburbs/exurbs are fundamentally uneconomical in general - most of the cost of housing comes from the land, of which suburbs are fundamentally wasteful. Literally everything there is (relatively) uneconomical, and is only widespread because the alternative is literally illegal.