It took me a long time to realise the point of learning 'phonics' at school (they were called phonograms in Australia).
While I can see why writing and reading without speaking makes phonics look useless, for children, all of their language is initially communicated through sound. Putting a bunch of symbols in front of them and saying that it has meaning isn't going to help them - but showing that the symbols roughly correspond to sounds that they already know have meaning is a pretty important step.
This doesn't apply to all written languages - logographic systems obviously don't have a correspondence between sounds and written symbols - but for alphabetic systems and the like it's quite a good system.
Of course, English uses 26 letter to represent 44 or so sounds, so as far as learning to read and write via phonics goes, English is one of the worst examples there is.
What you really want, for learning to read and write via phonics, is determinism -- you want someone to be able to write something if they know how it sounds, and to be able to read something if they see its written form. There's no need to have symbols and phonemes correspond one-to-one, and they generally don't even when people are devising their own orthography in a green field.
For example, using C for a generic consonant, we have the following regular spelling rules in English:
aC -- TRAP vowel
aCe -- FACE vowel
eC -- DRESS vowel
eCe -- FLEECE vowel
iC -- KIT vowel
iCe -- PRICE vowel
oC -- LOT vowel
oCe -- GOAT vowel
uC -- STRUT vowel
uCe -- GOOSE vowel
The rules for pronunciation is very directly linked to the spelling, with few exceptions.
Sure, as long as you assume the only goal is to validate a phonics approach to teaching reading. Some people appreciate that english words get the same spelling in Minnesota as they do in Mississippi.
For foreigners like me that mostly use it in text, the biggest overhead is in speaking, for example I always mess up the words study and student, it's infuriating.
Even if there are dialects that pronounce the same word differently, you could still find a lot of common ground.
If your biggest problem lies in a circumstance you rarely encounter, arguably fixing it is not a priority.
> for example I always mess up the words study and student, it's infuriating
This is a funny example to use, since it fully conforms to the rules I described above -- study uses the STRUT vowel, and student uses the GOOSE vowel. It would be a better example for the complaint that we have more sounds than symbols.
It's like a config file specification that supports gotos.
It's like in English, if you say "y'all" and write "ladies and gentlemen", you understand that those might mean roughly the same thing but are different words. It's not a spelling issue.
This is an important but hard to articulate distinction. Ask more if it's unclear...
English is somewhat conservative with spelling, so a lot of words embody their roots in their written form. Teaching kids to spell via phonetics and a huge set of rules makes spelling (and comprehension of new words) harder not easier.
Of course you can take this conservatism to absurd lengths: in French spelling and pronunciation have become so divorced after only a few hundred years that spelling bees are prime time television!
It is still somewhat phonetic. If you ignore the vowels that have changed sound over time and the silent letters, you can still sound out a fair chunk of English words.
Um.... there are plenty of characters that would, at first glance, appear to be identical to each other. There are plenty more that people have difficulty identifying out-of-context, but not when they appear in context. Characters don't get dropped for being hard to recognize.
They are easier to read, assuming you already know them, because they encode significantly more information than a phonetically-based script does. That's a fairly straightforward example of more work up front allowing less work later, much as encoding wikipedia into a decompressor allows the compressed version of wikipedia to be very small.
But memorizing a decent inventory of characters is a process of several years, and the boost in ease of understanding is under normal circumstances too small to notice. I notice that communicating in characters is easier because I'm not a native speaker of Chinese, and the semantic content the characters come with helps gloss over my lack of vocabulary and poor grammar. I can already understand English; I would get minimal help from extra semantic annotations to English text.
The total savings in terms of ease-of-reading in Chinese characters compared to an alphabet, summed over a person's entire life, will never pay back the effort it requires to learn them.
What do you mean by "learnable"?
The phonic connection to reading is overrated IMHO and this is why I wrote of a hack of the visual system. Kanji/Hanzi are so easy to read because over the millennia the ones that are hard to recognize at speed have bene dropped or tuned -- and they have no connection to sound, as you say (well, in the Japanese case in particular there are some phonological puns, but I doubt you notice them at speed, even if you have the historical connection). In the latin alphabet I almost never recognize puns when reading (though I get them immediately if someone is reading aloud). And when I was learning German I struggled at first to read the compound words but now the morphological decomposition is automatic.
In fact I think the trend to teach kids English via "phonics" makes spelling harder; comment back if you want to discuss further