Over the years, I've definitely gotten a fair share of calls from my bank asking about genuinely fraudulent charges, and calls notifying me that my card number

Over the years, I've definitely gotten a fair share of calls from my bank asking about genuinely fraudulent charges, and calls notifying me that my card number was reported by law enforcement as compromised and they're replacing it proactively. So yes, it does happen. (Of course, in the second case, they never tell you how they came to that conclusion, just that "something" was found.) Once I even had a card start reporting fraudulent transactions before I even had a chance to activate it, which was bizarre. It's also worth noting that different banks use different fraud detection algorithms, with different levels of sensitivity. Some card companies will call you at the drop of a pin, others are much more relaxed.