People will absolutely switch if another search engine is substantially better. But that's hard to do because Google isn't a lazy incumbent, their search is being continually worked on and improved.

Mostly other search engines seem to try to compete based on privacy or something, and while that's nice, it's not as tangible as superior core search functionality.

Like, DuckDuckGo isn't a bad search engine, and for a lot of things it seems about equally good. But "comparably good most of the time" doesn't make for a very compelling case to switch.