> Strustrupp didn't want C++ to C backward compatibility.
He certainly didn't say that in "Design & Evolution of C++" which goes through the early stages of C++'s evolution from C via "C with Classes".
> Why are people still writing ordinary C
Because they are targeting platforms without C++, or in case where it is (at least perceived that) C++ is unsuitable (too much dynamic memory, polymorphism, ...: too hard to predict exactly what happens). Eg. consider code for a low power embedded system running on a PIC controller with memory measured in hundreds of bytes (or less). And then there is inertia.
> Yes the survey is inaccurate
Of course it is. As every such survey (whether COBOL marketing from MicroFocus or a survey of job advertisements to name two that regularly generate headlines) it is massively biased because of its selection of data sources.