For some reason, I was thinking of the term taxi as a service rather than a vehicle that provides the service. I thus failed to see the plural form of the word and found that it was just a stupid gaffe. It is like failing to count by saying, "Three proud words: made in the USA." Embarrassing.
Or better yet, a better alternative would be, "Is there a taxi here?", because it sounds natural. Anyway, you are right that there is grammatically no difference in the Russian tongue (and theoretically no difference at all). However, context is what adds the difference, but I see no reason to not add that sentence as correct.