Check out “S” not for Plural? by rogersgeorge. Here is an excerpt:
Not much of a lesson today, but slightly autobiographical.
I think, and have thought so for years, that “-s” being the ending on a singular verb is a little incongruous (weird), since it’s also the usual ending on plural nouns. I frequently see people whose first language isn’t English get this…
The full article is available here.