Actually, the barristas at Starby's make almost no difference - they have a specific process using standardized machinery. It consistently makes average drinks, but the key word is 'consistent'. Nobody goes to Starbuck's for *good* coffee, they go there for *familiar* coffee, no matter where they're travelling. But yeah, because of that, quasi-trained monkeys can operate the system and produce a drink.

Of course, if a barrista deviates wildly from the process, then you get variances, and they're never good.