When I did it it had a chain and padlock but the door was bent just enough to be able to squeeze in, if its wide open now I'm also surprised it hasn't been utterly trashed.
Ah ok, that's unusual. It's normally wide open. I've lived in the village about 10 years and only seen it locked up for a matter of weeks at a time before it spends months open again. We used to hang about in it as early teenagers, drinking and smoking etc, but the thought of trashing it never even entered our minds. Presumably that mindset has continued with kids in the village.