The Homebrew folks think this is a non-problem. You may agree or disagree, but the pull request is certainly a non-solution to this maybe-problem. Not just because it gained zero traction and did not get merged anywhere, but also because it's just an obscure band-aid. Either opt-out anonymous telemetry is a good idea, or it's a problem. If to you it's a problem, advocate for its removal in its entirety.
So even if I have an issue with telemetry, good on the Homebrew maintainers for ignoring this MR.
The status quo is different variables and even different mechanisms for each program. Many badly documented. Only out of context is DO_NOT_TRACK obscure.
I think you know developers who reject informed consent will never adopt an informed consent model. The proposal was the best users could hope for realistically. Did you never compromise?
So even if I have an issue with telemetry, good on the Homebrew maintainers for ignoring this MR.