I'm trained to a certain degree (part of my maths degree is statistics) You are indeed right, it's the chances of 3 being within any "local area". There's also the fact that people only notice something when it's different from what they expect. E.g. people who think that all women are bad drivers will notice any woman who drives badly, and think "There, that proves it". They'll miss all the women driving well, or the men driving badly. Another thing is "wouldn't it be odd of odd things never happened" - if something has odds of one thousand to one of happening any given day, you'd still expect to see one every 3 years or so. If you went 10 years without seeing any, that'd be far weirder than seeing it 3 or 4 times! Hope some of that makes sense.