Evolution is slow. Evolution goes by trial and error rather than absolutely optimized engineering design and QA, and doesn't have any kind of recursive ability so as to improve its own methods.
On the contrary, evolution's QA is performed at all levels, while human QA usualy only deals with the upper functional layer. Nature's products are recursively made from 100% reusable, self-healing parts. Where are the equivalent robots that fix themselves at a molecular level? Different processes, different advantages.
While human tools can outperform nature for a specialized purpose, evolution produces more robust and general-purpose entities, that can easily adapt to new conditions. We don't have anything like that with human engineering (yet). While we can generate our own accelerated evolution processes, nature has a huge head start.