Like Ultramarina we know a lot of alternative minded folks who don't hothouse to the point of avoiding early academic development, this was particularly the case when our eldest was young. She went to a very alternative preschool and school, where I would hazard most of her (tiny) cohort was at least MG with at least one PG child in her group (of 10). NONE of them started school really reading. Most of them were truly reading by mid year, novels by the end of the year (ie way beyond normal reading progression, though to varying degrees). Except my own DD of course, who has multiple learning issues and was still working on the alphabet 2 years later. But because of this cohort not being academically encouraged before school she had looked perfectly normal until they all finished preschool and went to school... None of them had been supported to learn to read, all of them were advanced in general knowledge, problem solving, etc. Certainly some more than others.
On the other hand the school we moved to next was a high end private full of hothousing families... Our 2nd daughter is HG+ and has learned at a far faster rate than most of her peers - but again did not look developmentally unusual amongst a group of super enriched 4yr olds because she was doing sandpit and dressup while they were doing Kumon...
I think given these sorts of differences in approach to early life, when combined with the rarity of actual 99th-99.9th++ kids, it's little wonder teachers think "it all evens out".
Ironically enough though we have been told more than once that children who are as behind as our eldest was in yr 2 do not ever catch up, let alone get ahead like she has. So apparently it's only the kids who are ahead who are expected to "even out", not the strugglers.
