I far as i understood license detection in github works only for open source licences that are part of “choosealicense.com”.
“choosealicense.com” itself suggest adding a license to a github project but only jumps from one extreme to another, either open source or nothing.
But there are many non-commercial licenses that would allow software and writings to be used in many different ways.
Although github does not forbid that a repository add other licenses, it can be seen as hostile towards these works to let github not detect those automatically, although the reason behind it was probably only simplicity…
Anyway, i’d like to see the license detection enhanced so that githubs detects and shows license attributes of non open source licenses.