Partially true. For instance, many vendors ship a free (C) compiler (or make a free compiler available for download), which tend to not be very good. However, give me a commercial, paid-for, C compiler anytime. It tends to build faster binaries than gcc (which doesn't mean gcc is bad, not at all, but gcc targets a wide range of platforms, and its developers usually don't have the same intimitate knowledge of the OS as the commercial vendor does). I've build perl with both commercial compilers and gcc on the same platform, and most of the time, perl build with a commercial compiler was faster in my tests (although never more than 25%).

Another is that Solaris until recently shipped with a very early Perl (5.003, IIRC).

Not my experience at all. AFAIR, Solaris went from a "no perl" policy to "whatever is newest when the Solaris code freeze happens". Alan Burlison was always pretty keen to have the newest Perl included, although I don't think he's involved in that process anymore.