Anonymous commented on my Chief Of Licensing post pointing out that there's an entire organization devoted to open-source licensing and (s)he itemizes nine of the licenses managed by the FSF.
I had thought about the number of open-source licenses out there and I've written about it before, there are more than the nine highlighted by the anonymous post. You can read about Microsoft's attempts to bring standardization to their own licensing model here.
The point, however, is that there are far fewer open-source licenses than there are Microsoft standard licenses. More importantly, all the closed-source vendors will negotiate individual terms of their licenses with their customers. It is not unusual for an individual customer to have multiple instantiations of a single license with a particular vendor. The number of closed-source licenses any particular closed-source vendor will have is indeterminate as each one is individually captured in a unique sales contract.
There have been many people complaining about the number of open-source licenses that exist. I favor license simplification and don't want to see a wild proliferation of open-source licenses either.
Don't overlook one of the major benefits of open-source software - license standardization. This is accomplished precisely because an open-source license is non-negotiable. The infinitely negotiable closed-source licenses are the main reason the closed-source companies need licensing chiefs.