That is what I figured.
Usually, white on white tallitot are worn by Sepharadim, who tend to be mahmir on these kabbalistic inyanim. I would think this is why Sephardic siddurim, sefarim, etc. tend to be white.
I personally have 2 tallitot that have black stripes for shabbat and yemei chol and one with white stripes that I wear for the yamim noraim.
The entire inyan of Shabbos levush is very serious, and it is directly out of the Gemara. (Shabbat 119, IIRC).
And I stand corrected- I must have misheard in some article I read that the Romms were goyim.