If you think about it, escalators are kinda weird. They have stairs, except the ones that don’t. They go where you want to go, except the ones that go in the complete opposite direction. Also, you stand still, yet you’re in motion. Plus, there are handrails that move at the exact same speed as the stairs (or non-stairs, as the case may be). You don’t see that in nature very often.
So it’s no wonder this dog is all like “Dude, WTF?” and can’t quite wrap his brain around the machinations involved here. All he wants to do is move forward. Why won’t technology let him? Why why why? Short answer: dogs are awesome and technology is meaner than those robots in I, Robot (which, for the record, weren’t particularly nice).