Customers vs. sales transactions
Today the CBC reports that Tim Horton's will close its storied shop in Kandahar:
After having served 2.5 million customers over the last five years, the Tim Hortons [sic] location in Kandahar, Afghanistan will close at the end of the month. […] Since opening on Canada Day in 2006, the Kandahar Tim Hortons [sic] served four million cups of coffee, three million donuts and half a million iced cappuccinos and bagels, the company said in a release Thursday.
I presume that the writer means 2.5 million sales transactions, not 2.5 million customers. Given the unique geopolitical nature of the location, I would wager that most of those transactions were made by a small number of regularly returning customers (each of whom no doubt bought a net many more than the mean of 1.6 cups suggested by the figures).
If I have a small business selling coffee, and a solitary dedicated fellow comes into my shop three times a day for a year, have I served a thousand customers, or just one?