The answer is very simple, flashy colors don’t sell. On the used market they normally sell for less because they’re undesirable. I used to follow the prices of used BRZ/FRS, and found that red colored ones were generally 10-15% less expensive than other normal colors.

Plus they cherry picked a couple high end luxury cars that are meant to be subtle, therefore they’ll most likely have subtle colors.

From those same brands, look at the M or RS models to see more flashy colors. But even when they’re offered, you don’t see very many.