Minimal Landscaping in Urban settings

It is only something I noticed doing some of my research for 3D model purposes.  Of the places I have read about and seen (and believe me, there are a lot of places), I have noticed fairly minimal landscaping in the streetscapes.  Some streets do have some of the basic items: trees and grass strips, but there are some scenes with almost no landscaping to speak of. 

In my opinion, landscaping helps create and liven almost any space, not just the urban.  Multiple plants and flowers can add to the scenery, generate interest and there are some positive benefits to having more green in human environment.

Regarding the samples and other similar areas with less landscape, the form and feel of the streets have their own appeal, worth, uniqueness and charm.  However, it seems somewhat empty so little landscape. 

Some of these streets may have facets preventing the addition of landscape, though some free planters or other planter-type landscaping could still be added.  Its more of a personal preference and admittedly there are times I think the landscaping in an urban setting could be too much.  Particularly, I have been considering this in the 3D model currently in progress.  As an aside, this wasn't considered for some of the other projects (some of which are of a larger scale physically, where a "landscape clutter" would be more apparent).  Perhaps, it'll come up when I get to presenting and reviewing those models.