I noticed the same thing when I first started writing CGI apps in the mid to late 90's. I guess that the success of PHP as an alternative to Perl is mostly linked to its ease of redeployment on different hosts. All that the average person needs to build a dynamic web site with a database back-end is already buried in.

With CGI - and worse, FastCGI or mod_perl and mod_rewrite like some infamous templating systems I won't mention here - switching from a host to another can be a royal PITA, unless you have a good degree of control on the target machine and on all the needed modules.

I love Perl and loathe PHP when you need to solve a computing problem, but most of the time building average web sites with PHP is simply more sensible. (This is not a flame bait - I wish I could use Perl instead...)