Where would you put a search engine server for max privacy?
Say you want to build a privacy-centric search engine that uses a novel advertising model (or at least not pay-per-click) that does not require tracking of users. Where would you want the server to be physically located? What else would be important (encryption standards)?
Turn it around, if you don't keep any user identifiable data (including logs etc), then the jurisdiction where the servers are doesn't really matter.
Searching based on hashes of the words is one improvement on the status quo that you could do. Hash every token in the documents, then when a user does a search it hashes the words in their query locally and sends that to the server. This reduces the information communicated to the server and reduces the value to an attacker that gets the logs.