Do you really think you have a holographic sign floating above you that tells them you are a citizen? How are you sure you are above suspicion to be an undocumented immigrant? Could you prove you aren't if some goons decided to pick you off the street right now or next time you go for a walk?
All this is about expanding the reach and normalizing abuse of the power of law enforcement, just like back then after 9/11.
It's like Germany in the 1930s again when Jews were required to wear a yellow star on their clothes, but the other way round.