because it interprets "/" as mathematical division and "vs." as comparison.
they chose to use some specific, static operators so that you can do interesting things with the data, instead of having it simplify your request to what you "probably" want.
how many non-mathematicl non techy people (who realistically might want data like this, say, for a school report) would use vs. rather than /. it's just not natural english.
I understand your point: and I would have figured it out. But this is marketed as an everydfay search engine - which it's not, it's an advanced search for an encyclopedia :)
how many non-tech people would even assume that the search engine could produce this type of comparative results without learning about it first? in that process of learning, you learn how it works, and learn that /=division, vs=comparison
i imagine if it turns out to be a common problem, they'll probably give you a little reminder message about it. "if you're looking for data comparison, use vs. instead of /"
That little learning for technically literate (small percentage of users) could be a show stopper for the rest. Many people are scared of even the simple maths (sad but true).
they chose to use some specific, static operators so that you can do interesting things with the data, instead of having it simplify your request to what you "probably" want.