Just because Honda paints it doesn't guarantee anything. They are just body shops that have a Honda emblem on the door. They use different brands of paint based on what the supplier offers and what works best for the painter. There is not one specific brand of paint/clear/materials that Honda uses.
Lots of things factor into what the end color of the paint will be besides the color. Air pressure, distance the gun is from the panel, speed of movement, humidity, color behind the paint (primer, etc). It's just something that more colorful colors have to risk.
If you actually look at a lot of brand new cars the bumpers don't match right from the factory. Especially the silvers, This is because they are painted at a different location and place then the rest of the car. What really sucks is when you get ****ty customers who expect it to match when it didn't when it came in, even if only half of the bumper actually got paint on it.
black ftw