Beg pardon? Open up a terminal and type "ls -l /usr/bin/perl"...
The OS X libraries for PERL are there but PERL itself is not, they are not installed. . . and not active. PERL has to be installed. You get the same thing for RUBY, etc. The libraries are what you are seeing in the bin folder. So are the libraries for quite a few UNIX™ things that are simply not used. They are there if you want to use them. Then you would take an active step to install PERL to make them available. To do that you would have to enter:
curl -L http://xrl.us/installperlosx | bash And then license it for your use. Apple makes it available for download.
By the way, not all installs of OS X even have the libraries. My MacBook Air, for example, does not. Space on Flashdrives is at a premium.
Did you by chance opt to install XTools at any time when you did an install? That will get you most of those additional UNIX™ libraries installed.
By-the-way, the folder is there on my Macbook Air, but it's empty. Seems the install created the folder, but did not populate it with the libraries. I haven't checked my big install on my iMac, but then I installed a XTools on it. . . so I expect it's got everything there.