It does appear small in this photo, and I'm sure that visitors must feel tempted to lean over and touch the echidna(s). I saw a man pet one in San Diego's children's zoo last year, and the echidna didn't even budge an inch.
The indoor area is bigger than it looks in this photo as it goes back into the main shed behind. It's certainly bigger than the outdoor area, which I suspect is not too often used. Although I agree entirely about the height of the barrier!
