Los Angeles is spread out because it had functional mass transit at the turn of the last century. The Red Car interurban line sprawled out from downtown into the county and housing popped up six blocks on the side from every stop. Later mass car ownership filled in the blocks further out and the space in-between stops.

In that same period, just about every large town and small city had a trolley line.

You don't need skyscrapers for mass transit. Just enough political will to keep it funded.