What special knowledge or skills about coffee do baristas have? What special knowledge, training or qualifications do baristas receive that make them more expert on coffee than any other front line food service worker or interested home coffee consumer?  I don't mean simply operating the machine, but the why's and science that contribute to better coffee.  How do they get this knowledge?  Is there an industry standard certification or qualification that demonstrates them?

Bottom line:   I would like to know how the knowledge base of baristas is deeper than simply operating the machine, if in fact it is.
What you're asking is no different than: what special knowledge or certification/license do bakers have other than operating the oven? Many people know how to work the oven, but can they bake an artisan loaf? Do they even know the different kinds of bread? 

The same answer applies to baristas.  Some chains like *bucks have their own training program. Specialty shops chase baristas like the Neapolitan pizza parlors chase pizzaioli.  

The special skill? Besides the latte art which seems more of a North American thing, it is very difficult to pull a great espresso shot and choose good beans. I personally have been pulling shots on a pro machine daily for 7-years and still take my hat off when I meet a good barista. What you get from one of those Nesspresso or other superautomatics is the equivalent to microwave dinner lasagna vs Mario Batali's.