If someone at the store called the cops then the kid will own them. If the bank OK’d the purchase that should have been the end of it. Having worked in both retail and in transaction settlements I can tell you that involving the police is NOT the store clerk’s job.
FWIW I’ve made *much* larger purchases with debit cards while dressed like a slob and never had a problem. Smart shopkeepers know that if you treat your paying customers like criminals, pretty soon only criminals will walk through the door.
Yeah, it’s hard to justify calling the cops on him for being suspicious, if he satisfied all their normal protocols for a purchase. Plus, if they can’t show they were treating white customers making similar purchases exactly the same, then they are really screwed.