im guessing that this zoo does koala encounters or photo sessions of some sort? in that case this is a fairly common set up for that sort of thing and you appear to have just happened to get there between feeds.
Why not? As torie has already stated, Baldur arrived between feeds. Many places in Australia keep koalas in facilities just like this, and they do quite well. Chances are there are other enclosures off-display so the animals can be rotated.
This is pretty typical of koala exhibits in Australia in my experience, the only exhibits I've seen that didn't look like this were at Taronga, and one of Lone Pine Koala Sanctuary's enclosures which kept a koala on a live tree (the rest of their many koala enclosures all looked like this though).
