> So 81,604 lines for src/core vs 17,263 for OpenRC. So why does systemd need 677,446 lines of C code in its entire tree if src/core is 81,604 lines?
Do you want a real comprehensive answer to this? You can just skim through the code to systemd to see what it's doing. Just in my experience, systemd has a lot more features than openrc; you could also read their respective documentation to get a full picture of what they do differently. All the other additional lines are for other optional daemons.
I have been using systemd in debian for years and nobody I know has needed to pay Red Hat. That's just not really how open source works at the distro level. To the contrary, I've seen a good number of debian users/developers contributing their expertise upstream to systemd, as well as fedora users, arch users, etc.