The reason beginners choose PHP over Perl is due to Perl's dual blessing/curse, namely TIMTOWTDI and CPAN. The proliferation of Perl modules and umpteen choices at every juncture have resulted in very few focused books on Perl web development. Hell, many of the Perl community even distance themselves from the field of web development as if it somehow tarnishes Perl. Contrast that with PHP where the language is focused. Result: a plethora of PHP web development books aimed at all levels of ability. Perl never tried to compete with PHP as far as beginner mindshare is concerned. It was game over before it had begun.