[...] The logistics of a food establishment that seats between 20 and 25 people (which roughly corresponds to the definition of "cozy") are such that the place will stay afloat—barely—as long as its owners spend all of their time on the job. There is a golden rule, long cherished by restaurateurs, for determining whether a business is viable. Rent should take up no more than 25 percent of your revenue, another 25 percent should go toward payroll, and 35 percent should go toward the product. The remaining 15 percent is what you take home. There's an even more elegant version of that rule: Make your rent in four days to be profitable, a week to break even. If you haven't hit the latter mark in a month, close.
A place that seats 25 will have to employ at least two people for every shift: someone to work the front and someone for the kitchen [...] Budgeting $15 for the payroll for every hour your charming cafe is open (let's say 10 hours a day) relieves you of $4,500 a month. That gives you another $4,500 a month for rent and $6,300 to stock up on product. It also means that to come up with the total needed $18K of revenue per month, you will need to sell that product at an average of a 300 percent markup.
[...]
[...] the coffee [ed: with its acknowledged killer margins] needed to account for all of our profit. We needed to sell roughly $500 of it a day. This kind of money is only achievable through solid foot traffic, but, of course, our cafe was too cozy and charming to pop in for a cup to go. The average coffee-to-stay customer nursed his mocha (i.e., his $5 ticket) for upward of 30 minutes. [...].
Since the article both starts and ends with the observation you've tried to damn it with (that the owner of this coffee shop didn't know what he was getting into), I don't think that alone is a compelling response.
Finally, your analysis assumes that the coffee shop market is divided between "Starbucks" and "Independents". It is not. Other chain coffee shops account for nearly 30% again as many shops as Starbucks does.
PS: Respectfully, I'm not sure the guy who starts a thread with "coffee shops are pretty much the opposite of money losers" and "coffee shops have a 10% failure rate" gets to write smugly when his own revised math reveals his numbers to be wildly off, or his primary data point about coffee shops to be a single study from an industry marketing organization that included Starbucks in its numbers.