Similar thing happens at a much more micro level as well. I was an RA on a large scale research about discrimination, where people were asked to mention an incident they were being discriminated against because of their race, religion, gender, etc. The only demographic that had one common incident happening to them significantly more frequently than any other incidents were blacks (men and women), and the incident was being followed by the store staff when shopping. This would happen at various levels of income and education; meaning you could be a black person with a master's degree earning $100,000 a year, and you would still be likely to have experienced that.
I sometimes wonder how much of this is actual bias and potential racism, and how much of it is conditioned fear by the people in question.
I've been "followed" around stores many times before. It's usually smaller stores where 1 or 2 people keep an eye on customers, they will ask if you need help multiple times, if you happen to look around you can see they will quickly look away from you, they will keep moving to stay in a line of sight. That person is clearly watching me, whether they think I look like I might steal something, or if it is over-zealous assistance. As a lone shopper it also happens far more. In my mind I don't consider that I fit into a profile of someone more likely to steal than a couple shopping together, a little old lady, a middle-aged, well-dressed woman, but if I was a black person would I automatically associate it as "oh right, it's because I am black"? Obviously I'm never going to understand it from that point of view, but there is historical cause and effect at play here.
The other thing is, in these stores, who is doing the actual shoplifting. Is there a reason why they consciously follow black people around stores? To me people who steal things either do it from impulsion (there are associated conditions), because they can't afford to buy it, or they are drug addicts. As the research is only targeting discriminated groups, it would also be interesting to see personal experiences across all customers.