I think it's reasonable to point out that is not something most consumers are going to be able to do. The only meaningful search engine choice is that available

I think it's reasonable to point out that is not something most consumers are going to be able to do. The only meaningful search engine choice is that available within Safari. And you did install another App, they still aren't used from the system search on iOS, or from Safari itself. I think you might as well be asking regular consumers to root their device so they can use whatever Apps from outside the App Store, or whatever search engine they want. Also, even for a technical user, there is simply no way on an iPhone to change to a new search engine not already on a tiny list, and from talking with hundreds of consumers, I have not talked with a single non-technical person who could work out themselves how to change their Safari search engine to even one of the 5 limited choices, let alone a new option.