Compared to what? Some trees are very old. There's a bristlecone pine tree in California that has been around since before man knew how to smelt iron. What reproduces better than living things? Virtually nothing made by human beings is expected to last that long, let alone something as complex and intricate as a tree is. Some buildings, by luck and continuous maintenance, may last as long - but they don't self reproduce and only stay standing through massive ongoing repair.