Frameworks listed by you are widely popular and being used in PHP based application heavily.
In Indian market mostly people are using Joomla and Drupal for their PHP development, although it's depend on project requirements as well. This may be the reason that people are not much familiar with these frameworks.
I agree, there is difficulty to find the candidate having hands on experience on PHP open source framework.
In last year's PHPCamp, I expected atleast one talk on any PHP framework. But nobody gave a talk on it. (courtesy -
http://www.flickr.com/photos/jignesht/2879443512/in/set-72157607433097943/ ).
Well, in this year's PHPCamp you can expect a talk on PHP framework from me.
I also agree with Rahul, that people prefer to create own framework rather than using any open source framework.
BTW, I've been using above frameworks (only two) since mid 2007.
-Jignesh