Think about it, if you're a huge object, its going to be easier to break things your size.
Could you run through a really old door, if you tried hard enough? Of course. (Wooden door)
But could you smash through a hole the size of your foot? No.
Plus, I'm sure the bars on the fence are rusted, and of course they are old.
It takes a lot of thinking to understand it, which shouldn't be put in a movie. But it makes sense.