I would expect such a student to understand data structures and algorithms, language concepts, and other underlying principles for databases and operating systems. Yes, the passionate ones that are learning and participating in projects outside of class will have a better working knowledge and exposure to many languages. It goes without saying that it's not the best use of your time and money to be learning OO PHP at a university like Standford.
I wouldn't expect anyone to know object oriented PHP. However, if they have Stanford credentials, I would expect them to be able to learn it in a very short timeframe.
Also, a computer science degree does not make someone a software engineer.
What if the person did plenty of work outside the classroom, but it never happened to involve object-oriented PHP? I just don't understand the bizarre notion that if one hasn't written object-oriented PHP before, then apparently, well, I'm not even sure what the conclusion is supposed to be, but it seems to be along the lines of "you are a crappy programmer."
This seems a strange criterion. Do you mean that you expect all programmers to have written in PHP? Or do you mean, you'd expect a competent programmer to pick it up quickly?
I've been programming professionally for 18 years, and informally for 30. The most contact I've had with PHP is changing a couple of strings in an internal script.