I think, in all honesty, the issue with alcohol at weddings is likely a question of the average age of the attendees, which often is driven by the age of the couple. And yes, there are always exceptions, but in general, weddings I've been to where the couple married young and it was a young group celebrating often turned into the equivalent of a drunken frat party. Weddings I've been to where the couple was older and thus the guests were also older were much more in control.
So shots at a wedding is likely driven by the caterer or venue, but if you have a young couple you'll likely want to avoid them.