What were they thinking?

We were pretty certain that some of our trees were dead. When their lack of leaves this spring proved it certain, we decided to dig them out. One came out easily yesterday, so I tackled another one this morning. Instead of cutting roots I found myself trying to cut a thick wire cage surrounding the roots. Our yard was finished by a professional landscaper. Why wouldn't they remove the cage before planting it? Poor tree. I wonder if the rest of our trees have cages under them.