https://wiki.archlinux.org/index.php/Power_management
It can be a pain; enabeling sleep for every USB devices will likely result in the keyboard or touchpad becoming broken, increase the latency it takes to respond, etc. But once it's configured it just works very well. I'm getting 10+ hours on a Dell XPS 13" under light web browsing + youtube.
Any Apple laptop will likely need some unique customizations for everything to work and for maximum battery life. It could be argued that instead its popularity drives up the number of discovered errata. Case in point, the Archlinux page contains not only an extensive "Mac" page but it also has dozens of pages for specific Apple computers documenting pretty much everything you would need to know to get every feature working and get comparable battery life (could be a little better or worse).
https://wiki.archlinux.org/index.php/MacBookPro#Power_manage...