I wouldn't just write it off as a chip on their shoulder. I guess I can use a personal experience as an example but I can't really shorten it.

A few weeks ago I went to the pharmacy to pick up a prescription. I got there and saw there was a red line for where to wait to be called up. I just got off of work an I'm pretty tired and there is a chair right next to the line so I look up to make sure the pharmacist sees that I'm there and sit down to wait for them to finish with the person who got there ahead of me. Shortly after sitting down another lady comes and stands at that line. Once the first customer is done she calls the lady that just arrived. I think she probably just thought she was there first or doesn't like people not being on the red line. But I'm still pretty tired so I hope that no one else will show up and continue sitting. Right before that customer is finished another one gets there and stands on the line and is called up next. At this point I ruled out that they were just confused about the order arrival and was convinced that it had to do with them being a stickler for the red line. But I'm still exhausted so I decide just to wait it out sitting on the chair. Just before that customer is finished an older man walks up but instead of waiting on the red line like the others he sits in the chair next to me. As the customer leaves the pharmacist calls the older man up. I'm now just sitting there thinking if it wasn't the red line what could it be? Eventually, she calls me up and I drop off the prescription and leave. I went over what each other customer did and tried to find something that I didn't (and vise versa) but couldn't think of anything. the only thing that I could differentiate between me and the other customers is that I wasn't white. I'm not saying that situation had anything to do with race and chances are it didn't.

Overt racism isn't nearly as common as covert racism and a result racism is very subtle but still has a strong effect. That subtlety makes your everyday asshole and a racist person seem indistinguishable in certain situations. Which sucks for everybody because that's why these situations occur. Someone can incorrectly call someone out doesn't automatically mean they have a chip on their shoulder but because we are just human, no one is omniscient. Being incorrect really hurts both sides because then the accuser becomes the boy who cried wolf. And understandably many people who have been falsely accused previously or are scared to be, automatically side with the accused as knee-jerk reaction even before they hear/know the details. All of this just keeps an uneasy cycle going. It really sucks for everybody and it can only change when people take the time to see things from the other person's perspective.