AIUI the "Linux man-pages project" does provide the manpages you're reading, but only some of them. Specifically, its readme describes the scope as: "The manua

AIUI the "Linux man-pages project" does provide the manpages you're reading, but only some of them. Specifically, its readme describes the scope as: "The manual pages in this project document primarily the Linux kernel and the GNU C library, but also consider relevant differences in other kernels or C libraries. These pages are most of the section 2, 3, 4, 5, 7 man pages for GNU/Linux. A few pages are provided in sections 1 and 8 for commands that are not documented in other packages, and there are a few pages in sections 5 and 8 for the timezone utilities." Most manpages for individual command line programs are written and shipped by the projects or authors of those programs. And if there are manpages for functions in non-libc libraries those are generally provided and shipped by the authors of those libraries. The wide range of origins for manpages means there isn't going to be a single consistent style over every manpage in a Linux system (and of course "don't ship a manpage at all" remains a popular choice).