I can also post a ISO C++ one with similar results.

Or the video from Herb Sutter's talk at CppCon, where only 1% of the audience confirmed using any form of static analysers.

As anecdote, many enterprise places that use VC++ are still using versions like 2008 or 2010 and writing code as MFC/ATL had just been released.

The same kind of shops that are running Red-Hat enterprise 5, some Java version pre-8, and such.

I think my experience correlates with the study. Most lower level code that I had seen used neither unit-tests nor any good structuring. At least in close-to-hardware projects that seems to be more the rule than an exception. I think this is due to many contributors there not having a pure software-engineering background. Those often have not worked in other higher level stacks and therefore are not familiar with practices.