By a quick count, wikipedia lists almost fifty different open source / free software licenses.
Assuming (and this may not be valid) that many of these licenses were created in the early days of the movement, when it was trying to settle on common conventions, why do they all persist?
Given the seeming ideological split between the FSF and OSI, it is unlikely we would ever converge on a single common license. But much of the FLOSS movement is based on open standards, best practices, and so on.
What stops the FLOSS movement agreeing on a small set of licenses to cover, say, four or five levels of permissiveness, and everyone relicense to adopt them?