or they put it into crontab via @reboot ... . Or they run it in screen/tmux, or they will run it from crontab via @reboot which will start screen/tmux session with sudo for specific user..that's what I've seen myself so far on Linux servers. I believe having simple structured unit files saved us from part of such setups at least. Another big part is [hidden] under Docker now.
Seen nothing of that chaos on FreeBSD servers, but not cuz it's init system is superior, but cuz literally 0 presence on server market.
https://stackoverflow.com/questions/4018154/how-do-i-run-a-n...