I disagree. We don’t have laws that grass is green or that the sky is blue.

The idea of writing a law to make Māori or NZ Sign Language official languages are to enshrine access, as in if you are dealing with the government you can use these languages and the government must allow it.

We don’t have it for English because it’s the defacto official language, writing it down in law is fine but having an entire bill just for this purpose is a dogwhistle to racists.

Here’s an article that touches on it:

It’s not common for Anglosphere countries to have English as an official language, says Louisa Willoughby, an associate professor of linguistics at Monash University in Melbourne. (Canada is an exception, where English and French have equal status.)

This is because, as Adams said, English is already the default.

“People tend to legislate around language when they’re worried about preserving that language,” Willoughby says.

“It’s hard to make a legal argument that English is threatened in New Zealand, Australia, or the United States, for example.”

What, then, would the proposal change?

“Nothing,” says Andrew Geddis, a professor of law at the University of Otago.

Legislation is intended to solve problems, he says. “What is the social problem here that requires a solution? English is already an official language. It can be used in all public settings.”

Basically it’s quite unusual for an English speaking country to feel the need to write that in their laws.