PHP Sucks
evertpot.com
evertpot.com
It's hard to hire, people who are competent software engineers don't want to work for a PHP shop - because of the reputation - and people who are willing to work with PHP are often people who can't write good quality software.
It's not that good/great software can't be written in PHP it's that over the years it has gotten a reputation as a terrible language due to the propagation of bad coding practices and some quirks of the languages that haven't been true for 8+ years but people associate with PHP still.