Is it correct to say, "This is 1,000 people"?

Question

An infographic in a BBC article reads, "What does 500,000 people look like?" followed by, "This is 1,000 people," instead of "These are 1,000 people." I can see that it is an acceptable way of saying when talking about a group of things/people. It is, of course, correct to say, "This is a group of 1,000 people."

Just wondering in what grammatical sense this is correct.

Answer 1

The page depicts 1,000 people illustrated within one graphic or drawing. This representation is considered a single unit, which is why the singular is used.

They could have written “This picture is 1,000 people” or “This graphic is 1,000 people” (again, picture and graphic are singular), but they defined “this” with a visual representation instead of a word.