I'm not sure what you mean by "the idea of equality for all numbers". Initially all numbers are equally likely to be chosen. But, obviously, after some have been chosen, those numbers cannot be drawn again. When you start, if there are the same number of blue balls as of other colors, then all colors are equally likely. However, after drawing some, while the individual balls that are left are "equally likely" to be chosen, if there are now fewer blue balls, a blue ball is now less likely to be chosen.