Mini buildings in SimCity (2013)

In SimCity, when I zone land for residential, commercial and industrial, sometimes there is not enough space at the end of the zone to fit another building. Occasionally, these little strips of land appear, sometimes with a building or a fence. You can not click on these but you can destroy them. I have not found any information about them. Could somebody enlighten me?

Here is a screenshot that I found online:

The fence next to the residential building is an example, as is the fence next to the commercial building.