Standing ovations. Really?

The Melbourne audience stood and cheered for Mary Poppins. Why on earth would they have done that? 
            I've been told that the American passion for double-handed acclaim first arouse in classical concert halls. The Origin Story I have heard goes as following: ye suburban mid-century concert-goer in town from the suburbs for a night's dose of High Culture felt a crippling social anxiety during performances.  When the performance ended, feeling entirely out of his (or her) depth, and terrified of being viewed as some sort of Barbarian Invader crashing about in a Temple of Culture, he (or she) applauded wildly at everything. Just in case.
            And because everyone was – and is - at heart, afraid of being Found Out (Someone was applauding!  What do they know that I don't?!), everyone else began to join in, until as a matter of routine the whole damn audience clapped like maniacs.
            And now, more often than is pretty, instead of one’s lack of classic education being exposed through hesitance and confusion, the moment one stands up to bellow 'Brava!' one is exposing oneself as a clod. 
              There's no intimidating classical baggage around Disney music, darlings. If people will howl and bay and stamp their feet for this, one can only imagine what goes on in the New York Philharmonic. One presumes you get three curtain calls and a ticker-tape parade for showing up on stage in an evening suit with a cello.