I was mulling that over, too. Although it doesn’t seem to be too well represented online, there are instances of its use, one in particular (from Williston, Vermont) that I find convincing:
A. Although commonly thought of as just greens, squares or parks, the public realm includes the complete street-space—the space between the building façades: the sidewalks, street trees, squares, greens, and the
B. The street-space is a community’s first and foremost public space and should be just as carefully designed and planned as any green or civic building. The character of the street—both its scale and its details—plays a critical role in determining the quality of the place.
https://www.town.williston.vt.us/vertical/sit... (The document contains multiple uses of “street-space.”)
“streetscape” presents a bit of a problem in my mind as I tend to read its “-scape” element, first and foremost, two-dimensionally: the idea of a view or prospect. I realize this isn’t the sole possible reading— “landscape,” for example, can be (and is, e.g., in “landscape gardener,” etc.) read three-dimensionally. But even there, I find the two-dimensional element tends to crowd out the three-dimensional at first sight. “street-space,” on the other hand, immediately suggests three-dimensionality.