Typically these are uploaded in some other archive that may be less open (e.g. often outsourced to proquest or something), but many universities have their own open archives. My PhD thesis is available on MIT dspace. Hilariously, it's a scanned copy of my printed thesis, since I had to print it out for submission, even in 2015.
As for theses on GitHub, those happen but often people keep it private since they don't necessarily want the revision history exposed :).
Typically these are uploaded in some other archive that may be less open (e.g. often outsourced to proquest or something), but many universities have their own open archives. My PhD thesis is available on MIT dspace. Hilariously, it's a scanned copy of my printed thesis, since I had to print it out for submission, even in 2015.
As for theses on GitHub, those happen but often people keep it private since they don't necessarily want the revision history exposed :).