Because they can. Remember, in Perl There Is Always More Than One Way To Do It.
That is really the beauty of the language. You can choose whatever coding style you prefer and Perl will just do the right thing (patent pending :-)
A proper programming language should always try to help solve to problem, not trying to enforce the original designers misguided attempts at defining a coding style that fits everybody.
use Acme::AutoColor; my $redcolor = RED();
All colors subject to change without notice.