> because the sound/spelling correspondence is sufficient
I strongly disagree.
Firstly on listening to tourists, some of the worst pronunciation mistakes I hear are because they have learnt the spelling: you can hear mistakes that can only occur if you know the spelling (or are due to use a "general" voicing rule).
This shows up clearly when you are in another country and you tell someone a word for something and they repeat it back to you perfectly. However they often then ask for the spelling, and after you tell them the spelling, their pronunciation changes to something incorrect. Ouch.
Speakers with English as a mother tongue on seeing an unfamiliar word will ask how to pronounce it rather than making educated guesses at how to say it because any rule is often broken, and we learn not to trust our guesses. In fact someone who is well read but mispronounces words (intuited from spelling) is often laughed at.
One further problem that well spoken English is a sign of a good education, and it is often used to judge social status. In a professional job, correct speech helps one a lot. On the flip side you hear tradesman avoid using "correct" speech because they don't want to associate themselves with "suits" (or it is a group identity thing: I am not a ethanographer!).
The result of the above is that most people find it rude to have their speech or spelling corrected because of the implicit "I am better than you". Which means it is difficult to find anyone that will correct your mistakes because most people are polite. The exception is children: they love to correct adults and they often don't mind repeatably correcting pronunciation errors.
Note I think that a child that speaks English learns "rules" for sounding words primely to help identify the spelling of words they already know how to say. A learner may guess at a spelling, but the spelling is then corrected by the teacher.