I never really understood the rationale either, but we are talking about shitty colorbond rooves. For non Aussies that's a tin roof, western Sydney new developments are plagued by this, a dystopia of zero trees, houses with dark rooves that almost touch each other and surprise surprise, temperature breaking new records every summer.

Why it is more expensive to make a tin roof of a light colour rather than dark is beyond me. Why the government would give a fuck about greedy developers margins even less, but I have a theory.