I think it's general drivers that work are provided in kernel (aka. networking, video, etc.) and then any remaining ones are obtained via repositories, so long as your networking works, since including every driver would make the installation file enormous.
Well, for the more mainstream distros that have everything included, aka all flavors of Ubuntu. Some are rather bare and you have to sift through the repository in order to get the drivers. I'm not sure if linux can autodetect.