No Shoes, No Shirt, Maybe a Problem

So during this safety video on the train, the host mentions, "And be sure when you're moving about the train that shoes must be worn."  This is the second time I've heard that warning since being on the train.  Just makes me wonder how big of a problem travelers going sans shoes is.  And yes, I LOVE using the word "sans" as often as possible.  It makes me feel sophisticated....like I'm riding a train, wearing a top hat, a monocle and a tux.  Sadly, only one of those four are true at the moment.