The reason your Starbucks coffee is always a little different

You can find Starbucks anywhere now, just like McDonald's. If Starbucks is the fast food of coffee shops, then you'd think customers could expect consistency. To use McDonald's as an example, the chain hasĀ more than 14,000 restaurants in the United States, and a Big Mac tastes the same whether you're in Minnesota or Mississippi. How is that possible? Everything in the McDonald's supply chain is strictly regimented, down to the restaurants themselves. Beef patties are placed on the grill the same way and cooked for the same amount of time. Employees put the same number of dots of ketchup and mustard on every burger (via Reddit).

Starbucks strives for consistency, too, in its 15,000 U.S. stores. To help keep all drinks tasting as similar as possible, Starbucks uses superautomatic, push-button espresso machines to reduce human error (via Business Insider). No hands are required to grind or tamp the beans. Also, Starbucks is famous (or notorious, depending on your tastes) for roasting its beans longer and darker than other coffee purveyors. Starbucks says it does this to bring out the coffee's full flavor. The chain's critics, on the other hand, say a mass-producer of espresso drinks has no choice but to over-roast its beans to ensure consistency (via Medium).

Despite all these efforts at uniformity, however, it's not hard to find Starbucks customers who complain that their "20-pump vanilla, 20-pump hazelnut, whole milk, 190-degree, add whip and extra caramel drizzle latte" (annoying order via Delish) isn't the same every time. What gives?

The baristas at Starbucks aren't robots

The inconsistency at Starbucks might have to do with the seemingly infinite variety of ways Starbucks allows its customers to tailor their beverages. Maybe you only got 18 pumps of hazelnut when the barista made your "usual." Despite Starbuck's fancy Mastrena espresso machines, the company uses humans, not robots, to actually pull the shots and combine all the ingredients. Sure, humans are in McDonald's kitchens, too, but very little can go wrong when constructing a hamburger.

At Starbucks, that McDonald's level of consistency is hard to pull off. "We strive for consistency, but we are far from machines pulling the lever of a computer-generated beverage," a Starbucks supervisor posting as MaidenLocks said on Reddit. A lot of variables go into the quality of a Starbucks drink. Has the fancy espresso machine been calibrated properly? Has the milk-steaming wand been cleaned thoroughly? Did the finished espresso shots sit too long? Reddit user Yung__Lean put it this way: "Often as a barista I'm not completely satisfied when I finish making a drink. There may be a bit too much foam, or too little foam. The pumps in the syrup bottles may be freaking out, so there's too little or too much syrup in the beverage."

If you don't like the way your drink turned out, you can ask the barista to make you another one.