maizieD - as you have followed our discussions on various forums over the years, you know full well that I have a communication disability Auditory Processing Disorder (APD) which causes me to have word recall problems, and dyslexia, which is why I use references to research papers and research paper collections etc.
There is neurological development plateau from around the age of 4 - 7 years of age, when children develop various skills, and abilities at different ages, and at different rates, and it is only after the age of 7 that children move on from this plateau and are able to learn effectively. Also at this time all children naturally develop alternative compensating skills and abilities to work around their own particular weaknesses, deficits, and or disabilities. After this age any remaining development disabilities become a medically or clinically diagnosable lifelong disability.
The technology exists to test children even pre-school in the UK to check if children are cognitively able to use phonics before any formal education begins. And this would help the 10% of children or more who are not able to use phonics to be taught to read using a more suitable teaching system.
Teachers are able to adapt their teaching methods to meet each childs learning requirements, instructors only know how to use a single teaching method, which may not be appropriate for all children. (Children are not clones, thye are all different, different skill and abilities sets, and different weakness and disability sets) Currently we have too many instructors and not enough teachers.
Mashabell - as you say the orthography of English is the most complex, and could quite easily by simplified, as has happened in other countries that use our language, such as the USA. Language is only useful if others can easily use it to communicate effectively. Both Finnish and Italian are the purest languages in our writing system, and have less orthographic issues. However these countries still have their share of those who have Auditory Processing Disorders, Visual Processing Disorders, and Attention Disorders, which are the underlying causes of dyslexia. (and these same disabilities exist in societies that do not use a visual notation of speech communication system, and therefore have no dyslexia)
SantaIsAnAnagramOfSatan- if children were allowed to fully develop before the onset of Formal education, then they would be better prepared for Secondary Education, rather than have spent years being told that they are stupid, thick, if they have different natural development path to some oftheie peers, and if teachers were better trained to understand and meet their learning needs.
If you do want to read some research papers on the vast array of related topics, then you could browse through some of my PubMed Research Paper Collections