Perl doesn't just look for -T.

As documented in perlrun, Perl will look for its various command line flags on the #! line. It will die for -T because at the point where it is reading the command line it is too late for it to switch into taint-mode. Most others will work just fine.

UPDATE</b
Also Perl has a few other tricks up its sleeve. For people on very old Unix systems without a #! line, you can use perl as your shell and it will work. To see this in action try running the following with Perl:

#! /bin/sh
echo Just another Perl hacker,
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