Is there a heat dissipation reason why satellites are painted white instead of black? And if so, why are they white instead of a completely reflective surface?
Satellites are not painted white. Satellite bodies are are typically covered with reflective thermal blankets made of materials like Mylar or Kapton [1][2][3]. However, what makes satellites reflect enough sunlight to be visible in the sky is not the blankets but solar panels or antennas.
Why do you think they’re painted white? The flare itself is the result of reflections from the polished antennae which aren’t painted at all.
White and black are really the same colour, or lack of colour. The moon is actually like tyre rubber. But a tyre being lit by the sun at night is still brighter than anything else.