Sorry your wife went through that- it will probably be in the forefront of her mind in the future to grab the receipt from the self-checkout.

But to your white privelege emphasis and police wanting to search your car- I haven't had that direct experience but....

In 2017, we moved from a very white (Republican dominated) suburb where we had been renting for years to a house we bought in the central city (Grand Rapids, MI) to a very ethnically mixed liberal neighborhood & city. It was one of the parameters for our home search. Anyway, our home is on a fairly busy east-west road. One evening I saw police flashers outside my window and went to porch out of curiosity.

Across the street was a black SUV which the police had stopped. They had the driver, a black man, hand-cuffed and standing on the sidewalk while they rummaged through his vehicle. I went back inside but looked out again about 10 minutes later and the black SUV was pulled around the corner, police were gone, and the driver was standing next to his vehicle using his cell phone.

Conclusion, they pulled him over, did an unconstitutional search of his vehicle finding nothing and then drove off. Grand Rapids police had a history of such behavior which was well documented.