I have lived in a city with what in the USA passes for "decent" public transportation: Chicago. And I used it. But a "city" like L.A. will never have sufficient trains, because it's a giant county masquerading as a city. It's unlikely that a citizen works close enough to home to do anything except drive there.
That's why the endless proselytizing about "Let's be Amsterdam!" is soooo tiresome. We're not fucking Amsterdam and never will be. I love Amsterdam, but it's just not applicable.
Also the vilification of houses is obnoxious and dumb. The USA is not "full." Some people actually want to DO things, like garden or have a workshop or a swing set or a kiln. That means they want a HOUSE, and guess what? It's a hell of a lot better than covering up every square foot of ground with concrete for high-density apartment blocks, preventing water from percolating into aquifers and intensifying the permanent drought that reigns over much of the west.
Not to mention the "heat islands" that endless densification creates, and the trees destroyed for it.
The endless bellyaching by fake liberals about "zoning" serves as a smokescreen for corruption: a handout to developers and a license to destroy already-residential areas, while giant dead malls with boarded up Macy's stores and vast concrete parking lots sit growing weeds. THOSE have already imposed costs on the environment and are already "high-density," so until every one of those is redeveloped (along with every defunct commercial or manufacturing zone) we should never be targeting neighborhoods with actual HOUSES.
Zoning is USEFUL. It allows people to choose the kind of neighborhood they want to live in. People who want density and walkability have downtown. People who want a house can choose neighborhoods zoned for houses. And some neighborhoods blend the two pretty effectively. But pretending that zoning is always a racist, elitist conspiracy is infantile at best and more often an excuse to destroy neighborhoods for someone else's profit.