I have always wondered that too, but I think it is because of the different audiences of PHP and Python. There are Libraries->Frameworks->CMS's->Blog Platforms

I have always wondered that too, but I think it is because of the different audiences of PHP and Python. There are Libraries->Frameworks->CMS's->Blog Platforms. Python tends to have strong offerings on the Library and Framework front but no consensus enough to have a popular CMS or Blog Platform. Without popularity, a vibrant ecosystem never really develops. PHP has the tremendously popular WordPress and Drupal, but they were not made using popular frameworks or libraries so their code base appears quite messy and hackish. Also, PHP apps are very easy to get started with; either one-click installs on cPanel or drop this chunk of code in your web root. Configuring a Python web-server is still much harder for a novice.