The danger with rubber shoes like Crocs is not at the escalator disembarkation point where the flat steps disappear at the end of the escalator. The danger is before that point, when the steps start folding up and going away. Children are tempted to push the toe or sole of their foot against the step in front of them while it recedes. If you're wearing a hard soled shoe, there's not too much of a worry here. But if you're wearing flip-flops or Crocs or anything else made of soft rubber, there's a chance that the friction and the malleable nature of the shoe will cause some of the front lip of the shoe to get pulled into the crack where the step recedes into.
http://blog.havill.com/2009/03/crocs-in-japan-dangerous-on-escalators_28.html
http://blogs.consumerreports.org/safety/2008/05/crocs-escalator.html
be warned....
