> what you're really doing is giving legal standing to someone who claims to be acting on their behalf

This does not necessarily follow.

Who speaks on the behalf of the mentally handicapped, and children without parents? Are they people?

The simple answer is that we have over a thousand years of jurisprudence to answer that question. In some cases it's the next of kin; in some cases it's a state-appointed guardian.

But even with the benefit of all that law we still have many courtroom arguments over who gets to decide what is best for individuals who are only partially able to speak for themselves. When we move beyond natural persons and corporations, we have far less jurisprudence to rely upon and they can't express their desires at all, so it's harder on both counts.

Iwi.

I dug further and there will be two people who are in charge of representing the river one nominated by the government and the other by local Iwi.