unexpected meetup

In 1974, 4000km from home, visiting family, we were in a non-tourist suburb of Perth, Western Australia. One our first day, we popped into a small supermarket. We bumped into neighbours from our home town. We were unaware of each other's presence in Western Australia. There are many suburbs in Perth and, within any suburb, multiple shops at which one can buy milk and food. The chances of 'foreigners' from NSW choosing to go to the same section of the same supermarket, in the same suburb, of the same city, on the same day at the same time seemed remote. In 1999, I was 20000km from home, in Trafalgar Sq, London, when a friend from Sydney hailed me: the chances of Australian tourists being in London at the same time seems more likely, but the crowds in Trafalgar Square on a sunny day in high tourist season would have made it easy for us to not spot each other. Indeed, if the other person had not spotted me, I would have not noticed her as I was walking away from her when she hailed me. In 2000, I was in Rio de Janiero, riding an elevator to the top of Sugar Loaf mountain. The only other people asked me for information and I said that I was a tourist, not a local. They then said they were from Australia. So was I. They were from NSW. So was I. They were from the Illawarra region (county), so was I. We did not know each other, but we were from "The south coast" of NSW. Fewer than 500,000 people belong to our region. There are no direct flights between Rio and Sydney, so the number of Australian tourists in Brasil was fewer than would be expected if travel were easier/cheaper.