|Don't ask to ask, just ask|
Yes, but of the 90% of all deployed machines, over 99.99% will never have a user issueing Perl one-liners.
To do statistics in a meaningful way, the number of deployed machines with a certain shell isn't relevant. You'd have to look at the number of users (where a single person working on N platforms counts as N different users) that issue Perl one-liners. And I'm pretty sure that more than 10% of them run non-Windows shells.
Not to mention that Unix shells have been ported to Windows, and I do know people using Unix shells on Windows (myself included). I've never heard of the Windows shell having been ported to Unix, never mind any one actually running the Windows shell on Unix.
Oh, and MacOS has gone Unixy as well, so that's another platform that will have a Bourne shell compatible shell available.
As for VMS and other exotic OSses, my knowledge about them is too limited to comment.
In reply to Re^3: RFC: A Primer on Writing Portable Perl Programs
by Anonymous Monk