in reply to qr/string/ is not the same as qr/$var/ ?

This is not regular expressions problem, nor qr problem. If you try as:
my $foo = shift; print $foo,"\n";
and do
[ambs@eremita tmp]$ perl 'fo\o' fo\o
I know I didn't answer your question. Basically, it seems program arguments are quoted. Can't say why.

Alberto Simões