There are quite a few search engines available on the market. Search engines require a lot of codes in network and file accesses, which are often done using native support from the operating system to improve speed. As such, search engines are difficult to port across platforms. Don't think that this is too low-level a question to ask. A good programming language is an important factor on the quality, portability, and customizability of a software system.
Programming languages evolve very fast as well.
Search engines may be new, but the data access core of some of the products may still be based database codes developed twenty years ago. In the fast growing Internet world, unfortunately, older is not better. The web doesn't just contain HTML files. The search engine must be able to index and search a large variety of file formats. This is especially essential for corporate portals.