Obviously, we have different definitions of an institution. Mine is a colloquially accepted one of “ any familiar, long-established person, thing, or practice; fixture.” Starbucks is clearly a familiar, long-established thing and therefore qualifies as an institution, although not as august an institution as the Supreme Court or the Rotary Club, but certainly a widespread and widely-acknowledged one.
It is also obvious that race was a factor. There were 27,339 Starbucks in 2017 and I am quite certain that each and every one of them has to ask people to leave at one time or another for one reason or another. I’ve seen it happen myself on several occasions. The only reason that this particular ejection scenario became a trending news story was that these two specific individuals were black. Had they been white, we would never have seen this story because it wouldn’t have been a story, unless they had some other distinguishing feature, such as being elderly white men, or gun toting militia members. It was the distinguishing feature of their blackness that made this a trending news story and therefore, ipso facto, race was most definitely a factor.