I find Arch based distros have pretty solid hardware coverage. Lots of older hardware support baked in, plus newer kernels ( newer drivers ), and up-to-date device firmware.

The older the kernel, the less hardware is supported ( generally ). That is going to be a big reason for the disparity between distros. But device firmware makes a difference, especially for distros that do not support non-free binaries. Debian has gotten a lot better since they changed that policy for example.

The more desktop centric a distro is, the more likely they are to bundle a broad selection of hardware drivers.