Perl is much more terse for one-liners and has much more built-in for doing text processing in scripts. Stuff like implicit read loop, field separation, etc. I would say they're suitable for different jobs: if a perl script grows beyond a hundred lines (you can do a surprising amount in that space!), then Python may be the right tool.
Perl is also much more of a known target: some version of it exists on basically every single Unix, and the language really hasn't changed that much in the past decade. I have SSH'ed into multiple CentOS 6/SLES 11 (released 2009, and granted mostly to rescue data off them) servers in the past 2 years, and perl is just much more of a known target to write things against than whatever python release is on that system.
Having an implicit line- and field-splitting loop for standard input with a couple of command-line switches. (Awk doesn't even need switches, but is cumbersome if you need initial state.) This covers a lot of use-cases. Also, very compact and powerful regular expressions.
Perl is also much more of a known target: some version of it exists on basically every single Unix, and the language really hasn't changed that much in the past decade. I have SSH'ed into multiple CentOS 6/SLES 11 (released 2009, and granted mostly to rescue data off them) servers in the past 2 years, and perl is just much more of a known target to write things against than whatever python release is on that system.