And postcards frequently romanticly pictured buildings with more color and plant life than what was reality. Just like developers do with modern renderings of new buildings. They often embellish because after all, it is an advertisement for the building.
Texasstar is right though part of the reason the suburb was invented was the dirty grimy cities. Victorians added their own garden evolution to more urban areas but once buildings started climbing upwards the focus was less pretty trees and brick laid sidewalks but the progress of production and the industrial machine. Concrete and the strength of a human-built world was what people considered the progressive norm. Nature was a weak element and didn't belong in the human progress of cities. Not just factories were dirty and often terrible places to work but even shopping areas and particularly inner-city living involved lots of noise and overall lack of city services. Poor people and immigrants lived in the dirty cities while those who could afford the trolley ride to the further out areas were those who had greenery.