This.
Although I will temper it a bit by saying I could see how some of the bizarre answers might work. For example, saying "He's been in hospital" is common in Eastern Europe. Some of the sentence constructions make sense as literal translations from other languages with much different grammatical constructions.
What?
"He's been in hospital" is correct English. What do Americans say then?
For a lot of those it was very clear that the ones that weren't 'correct' English were really just either American or 'Ebonics'. We all know how Americans mangle the language!
Granted there were some questions that must relate to dialects I've never encountered, or that are from people importing the grammar of their non-English first language. But for most of them, the ones that sounded 'wrong' were just obviously 'American' rather than English.
Edit...Ah, so Americans put a definite article in there (to me that makes it sound as if there's only one hospital - "I was in _the_ hospital").
A web page somewhere says
"A few 'institutional' nouns take no definite article when a certain role is implied: for example, at sea (as a sailor), in prison (as a convict), and at/in college (for students). Among this group, BrE has in hospital (as a patient) and at university (as a student), where AmE requires in the hospital and at the university (though AmE does allow at college and in school). When the implied roles of patient or student do not apply, the definite article is used in both dialects."
...which I guess explains it. No dialect or language really makes complete logical sense, its mostly just about arbitrary conventions really.