A 10% margin also often doesn't tell the whole story of how they make their money. Nearly since its inception, a substantial portion of McDonald's long term profit came from the appreciation of the real estate the stores were built on. Operating a business on it just made it cash flow positive during the holding period. So it was essentially a REIT that happened to operate a fast food chain. Even for many mom-and-pop restaurants (or other business) the real payoff often comes when it comes time to sell and cash in on the capital appreciation of the business assets.
My point isn't to say there's anything wrong with that model: more power to anyone who comes up with a creative, legal way to make a living. Mainly I just want to point out that you often can't look at it simply as making X% margin on sales in a given period of time or any other single metric for many businesses as the real gain is longer term than that.
Which is really a long-winded way of saying: if the ability of a business to make a long term profit is not my concern, their claimed inability to pay a living wage isn't either. If they honestly can't afford to pay a living wage, then as the article states, perhaps it shouldn't be in business. If there is a market for whatever product/service they were offering, someone will come up with a sustainable way to serve it that is better for all involved.