Extra colours adds costs and complications for Honda. They either need separate body spraying booths for each colour, or shut down the equipment and delay production whilst they change the paint colour for a different batch of bodies. Plus the complications of producing the correct level of stock to closely match the level of demand for that particular colour.
The premium sunlight white pearl appears to have the whole body initially painted in a basic white paint, and then gets additional coats of the fancy pearly paint but only on the outer panels where it shows.
I suspect this is an additional spray booth stage which basic colour cars do not get. Sprayed by Robots maybe, but still adds to costs. Which will partly justify the higher price for some colours. The basic ,non pearlescent , white may be available as a lower cost option in some markets.
It may be my imagination but I think the extra coats of paint for the premium finish actually makes the metal body panels feel less thin and flexible. But may add a kilo or two extra weight.
The Model T Ford , a pioneer of low cost car production lines, was available "In any colour as long as its black "
