We obviously are not going to agree on this. Enjoy your vision of America where police can force a man to prove to them—based on ethnicity and one or two other atmospheric considerations—that he belongs.
Something needs to be done about illegal immigration. Very much so. But IMO this is a scary law. This legislation does too much violence to the individual freedoms we should value as Americans.
There should be no freedom to enter the country unlawfully.
Getting the illegales to self-deport by drastically curtailing their opportunities to get benefits or employment without first proving that they have legitimate business being in America, would probably help the most. Grabbing someone who might or might not be a legal resident is going, as you say, to bring big problems.