This kind of 3D model is easy and cheap to obtain. It is made of separated, lightweight geometry, ideal for large-area city models visualised on a budget. Excellent for background models and wide-area city visualisations where accuracy and level of detail are not that important.
The free model created from the OpenStreetMap dataset offers some third dimension to a map, but that is pretty much it and its level of detail is almost nonexistent.
OpenStreetMap
CC BY-SA 4.0
<a rel="nofollow" class="external free" href="https://www.openstreetmap.org/">https://www.openstreetmap.org/</a>