I currently use Fedora 38 with LUKS. I am tired of having to type my long passphrase whenever booting up my laptop, only to also type another complex, albeit easier password for my user account.
But on Android, for instance, you only need to memorize one. Why is that? Why can’t desktops (and laptops) work like that?
They can work like that, macOS (w/ Apple Silicon) does for example.
Android uses file-based encryption instead of full-disk encryption (which is what LUKS is), basically on Android only certain folders and files containing user-data are encrypted, instead of well, the full disk.
This is possible on Linux, you could use eCryptfs to encrypt only your home directory for example. It’s not very commonly used on Linux though, which in turn means it tends to be buggier than LUKS. So to really answer your question, Fedora developers just don’t seem to care about making the experience better when LUKS works good enough.
You could set up linux so you only get asked your LUKS passwords after you turn on the computer. Some distros like OpenSUSE asks you about that on the installer, but I think for that your system to have the same password as for LUKS which some argue it’s bad for security, I don’t necessarily agree tho.