They could have added Jackson Hole, Wyoming to the list and it would seem equally strange. Kind of a small town with billionaires that you don't really know about unless you've either been there or read specifically about it.
In Canada I'm not aware of any rich people small towns (unless you consider Vancouver, West Vancouver, or Toronto, or the Shaunhessy neighbourhood of Vancouver), but there is the Muskoka area of Ontario where Kevin O'Leary's wife recently smashed her boat into and killed someone
Plus all the multi-millionaires from nearby Northern Italy (one of the most industrialised regions in Europe until quite recently, and still one of the wealthiest) hiding their wealth in there. Them and Mina, the famous singer [1].
In Canada I'm not aware of any rich people small towns (unless you consider Vancouver, West Vancouver, or Toronto, or the Shaunhessy neighbourhood of Vancouver), but there is the Muskoka area of Ontario where Kevin O'Leary's wife recently smashed her boat into and killed someone