I don't think that can be engineered away in any reasonable way soon, so saying they shouldn't need to know seems irresponsible to me
Hmmm. It took me a while to figure out that you weren't referring to sites for angling enthusiasts.
Allowing the URL bar to also act as search or vice versa, the simple act of trying to do the one thing now does something else that you might or might not have intended or been aware of being possible is not the same as a single purpose choke. When that possible thing is sending your data to a 3rd party, then that is just bad.
Edit: finished an incomplete thought
Messing with URL and search is like messing with the steering wheel, or - in case of self-driving cars - with navigation input.
We could equivalently ask why ftp and http and https and such don't have different types of entry uis, since they're different protocols. If we consider the "resource location via plain language" protocol (which we could even formalize!) that defers to http(s), ftp, Tor, and Bing based on aspects of the request, it's just one higher level protocol.
Yet automatic chokes became standard, and today's drivers usually don't even know or care what a choke even is. Todays people have other things to spend their time learning.
People of tomorrow may not need to know or care what the difference is between a search box and a URL bar. All they know is they can type what they're looking for into any box, and they'll find it. And like the choke, it might turn out that most people might prefer not to know.