I just hatched out several eggs bought from Stromberg's and advertised as White Variety Egg Assortment, White, Texas A&M, Italian. They appear smaller than the Cortunix I have hatched. Let's see how they develop
Size is a genetic factor influenced greatly by the selection process of any particular breeder and not so much an indicator of quality. Also the majority of those chicks are golden color phases which, unless someone puts a lot of work into breeding them larger, are not particularly large color phases. Some goldens like the manchurians can't even be pushed past a certain size point. English whites are a good example of this as well, they cannot be bred to be larger than 8 ounces no matter what you try.