UEFI graphics drivers usually support much more fine grained modesetting than VESA, assuming you have a native UEFI graphics driver rather than one that's thunking down to a legacy BIOS option ROM. They're also (usually) capable of reading and parsing EDID and will set a native mode if possible. The number of people not running their desktop at their display's native mode is sufficiently low that it's not really worth worrying about.
That's why we switched to UEFI around a decade ago; I'm pretty sure it doesn't have all those problems. So a modern PC can boot directly into the correct resolution.
–Matthew Garrett (he wrote a lot of the Linux kernel UEFI implementation)
Mines an Asus Gene VIII and using a 1080Ti and I don't even get anything appearing at all until the Windows logon.
Every distinct piece of Apple's boot process (firmware, boot loader, kernel, desktop) can have the correct video driver, be aware of the desired final video resolution, and trust that any previous piece has left the video card in the proper state. It all ships together.
The PC BIOS doesn't know you want 2560x1600 for your desktop. It just picks a mode suitable for the BIOS. If anything, the BIOS is required to leave the screen in VGA text mode. The boot loader faces the same issue. At best, a Linux distribution might decide to use a VESA mode, but that can't cover the desired 2560x1600. (VESA doesn't go that high)