I would need to hear that from someone who actually works in a CC company fraud department because I don't think it's that straightforward. I've had MC transactions declined on a card I use for everyday purchases at two stores in my neighborhood. I don't think reasoning about their transaction monitoring like someone might monitor network traffic is a good analog-- they're specifically looking for patterns in small-scale, localized events without many data points. They don't have to connect the events to stymie the fraudster's efforts.