More like 0.01% -- if we consider enterprise programmers, web programmers, and application/game programmers which I'd expect to be the largest groups...
Yep. There aren't many software developers I know who have ever touched {Linux, macOS, FreeBSD, Windows} kernel code except for embedded devs, driver devs, security researchers, hobbyists, and SREs/PEs.
The % who have touched kernel bits, wrote a triangle engine scene renderer, wrote a compiler, touched server metal in production, have worked on ASICs, and can put together ML/AI building blocks shrinks way, way down to a handful of living humans.
This not about blue collar vs white colar. After all corporate programmers and web programmers can both be blue colar, and systems programmers can be white colar (if we're using "blue colar" to mean smaller salaries and fewer percs - otherwise programming is a white colar job anyway).
This is about how many work in kernels/embedded systems/etc vs more common programming gigs. And that's less about how many are trained to do so, but rather how many are needed.
