Part of Google’s strength is the simplicity of the single input text box. Many customised search sites have a user interface which is too hard and complex. With so many different search flows and options it’s over whelming and extremely difficult to find what the user is looking for.
Results are not always relevant to user’s search query. It takes too long to find relevant content. Users are not using correct terms, so cannot find the information they are looking for. Minor UI changes can significantly increase search usability together with overall UX.
Google also set the benchmark with speed. Search which is slow and takes a long time to return results, will not engage users and keep them coming back. Google’s platform and indexing technology is second to none. Google Cloud Platform and ElasticSearch bring that capability within reach of enterprises.