Also, dye costs money, and adds to the price on a diaper. Uncolored plastic is cheapest, most plastics have a natural somewhat opaque or clear color. White IS a pigment, and adding it does cost money, but white is the most common and therefor the cheapest pigment available. It's also very easy to be consistently white. Being consistently blue for example, means carefully controlling the
amount of pigment, lest you get slightly
different shades of blue.
But forgetting all of that "technical stuff", given a choice of solid colors, the only diaper I want is an all-white one. So much of this is mental for most of us, and white is what we came to associate with diapers long ago, so that's not likely to change. We want what we remember, what we're used to, and that's WHITE!
And years ago the diapers I remember coveting most were those worn by the kids stumbling around at friends and families houses, usually also wearing white t-shirts and socks, and I think that's why I also enjoy hanging out at home dressed the same, with a short, tight-fitting white t-shirt and white socks. I'm "living the dream" so to speak, I'm exactly what I was so jealous of years ago. And that's how I am sitting here right now too, wearing a short white t-shirt, white socks, and a fresh BetterDry, I wouldn't have it any other way!