There are so many reasons I can give about this but it'd take forever. So let me just say this, which is only a small piece of the puzzle: Students were dropping out of school in the 50's and 60's and It was thought in the 60's that learning to read earlier would get children to stay in school which of course has been proven a big mistake. And so there was started a big campaign to start everything early, Head-start, etc. which at first was only geared toward inner city children living in very bad conditions and not getting the proper nutrition, care, love or any proper parenting (most, not each). Parents that were having children one after the other to gain more monies in their welfare checks, parents not interested in raising healthy, responsible adults. It was found that these children were often very limited in their attention span and so the answer was to give them quick and short songs and such for the letters, numbers etc. and the sooner the better. The thought was that the sooner and more we can get in the more they would learn and want to continue to learn. But this has back fired big time. This spread into the educational system at large since and has taken on all kinds of aspects and damaging results. In fact the experiments and results that the system has done over time has been proven wrong time and time again and yet they insist on doing this way anyhow. The whole public has been brought into the lies. In the late 60's or early 70's the german government decided to try our way of educating the young. They hurried one set of schools along into early reading etc. and let the other groups continue with more play, singing, rhyming verses, more non-academic and learning through doing and they found in one years time the hurried children were much slower in their thinking, stressed, nervous and many displaying the beginnings of learning disorders. They went back to their old way of early educating. The way it is done in this country and others to give children an early start follows the notion that this will make them smarter faster, benefit them academically and later professionally and be first and more likely to prosper. We live in a supper competitive world so many people fall for this idea that quicker is better, especially when it is seen that children can learn early on. But enough evidence is out now (Harvard has mounds of evidence that the most of the public knows nothing of) that shows the dangers of learning academics too young, too soon. (I cannot go into all of this obviously here) For one thing, children introduced to academics early seemed to be at an advantage in the beginning but as time passes they lose this and many are unable to learn higher academics and later in life they are less personally satisfied with their lives and less socially integrated. The Scandinavian countries start their children later in formal schooling, 6 1/2 to 7 years, and have for a long time. Education in these countries is actual education, not training like it is here. At one time our system was the same and it has been known for hundreds, thousands of years that a child begins formal education at around 7 years. This is natural and normal for many reasons. It was also known that the relationship with the teacher was imperative, that love of the teacher for the child was everything. (but of course, at one time most people weren't formally educated either -- still these aspects are nevertheless archtypical) But since the early 1900's children start earlier and it just keeps getting earlier and earlier. This is very slowly changing. To start educating a child into early reading and the like is too much too soon and is at best misguided and at worst counterproductive and damaging. Remember too that public school teachers only know what they're trained to do by the government and are employed by the government -- unless of course they choose to expand themselves and question and venture into studies that show other and truer methods for truly educating a child. Also the word education itself is an ancient Greek word meaning To draw out. Our system pretends that children are buckets waiting to be filled. Reverence for education and the child is required for real learning to happen. "Wisdom begins in Wonder" --Socrates
There is so much I could go on about -- these are not just opinions -- many educators have more knowledge on this and many parents are questioning and gathering knowledge. There are many good books you can read on this - many mainstream, many not so mainstream. If you read about what the school system is really about you'd be horrified - even most teachers aren't aware. The system runs on this manifesto phrase which is updated periodically, "the purpose of the public educational system is to separate child from parent."
Also, you may want to check out the alliance for childhood. If you're feeling pressured about this just try to relax and let go. And remember no one is going to ask your child as an adult when he learned to read any more than anyone will ask when he was potty trained. Some people believe if a child can read early they will automatically become a productive, intelligent person but this isn't usually true. And so if a young child is a good drinker we should give him beer or champagne?
Take this as you will. This is only a very small bit of what is really happening concerning early reading and or academics, some reports say it has led to much more crime over the last 40 years. I hope this has helped in some way. Personally, knowing what I know now, I wouldn't have worried at all when my child didn't read as soon as others or thought it was so great that my other child taught himself to read at 4 years old. I mean this all in good intent and in good spirit.
The best to you