An individual wants a feature and is prepared to pitch in, probably worth the time investment for a maintainer.
The US government wants floating point arithmetic done a certain way, fuck you, pay me.
That, and also, there's a donation link in many of the repos. Why isn't it used as much as it ought to be?
The linked email is from an HPE/Cray employee interacting with the upstream gcc team, not from anyone in the U.S. government.
The U.S. Government, via lots of programs, national labs, etc. does pay people (and companies) to work on open source code. This has at various points included LLVM, clang, flang, gcc, and many other projects. We like it when things get upstreamed and we also contribute ourselves to these projects.
Certain companies' willingness to put in the work required to upstream has been an issue at times, but it is improving and it's something that we push on very hard.