Blue is a much better color for food prep. Not many things are naturally blue so they stand out better of a part of the glove gets in your food mix, white bits may look like fat or other food and black can easily be masked in darker ingredients.

This is why cooking ingredients like large butter blocks and bricks of fresh yeast are in blue wrap or blue bags. If you dump a few 40 kg blocks of butter into a mixing bowl with a few hundred kilos of sugar and flour then a small bit of blue is going to stick out like a sore thumb, black might also but add in black strap molasses or caramel color then you won't see black glove bits.

Correct, but black gloves are great at hiding even visible dirt.