It's true, EllenJane...everything you say is true. However, how is it true? Why is it true?
If the stats are to be believed, the rates of diagnosed ASD in children in the UK is 1 in 100 ref. 1 in 100 is not that rare. And, if we look at the 2009 data for SEN (Table 9) we see that 20% of Statements of SEN in Mainstream Primary schools were given on the classification of ASD. A further 3% of children in MS Primary schools were on SA+ with an ASD classification.
So, we can see from the stats, that in MS Primary schools, about 23% of the SEN that is severe enough to warrant either outside support or a Statement, is ASD. So not that rare. Second only to 'Speech Language and Communication Needs'.
My thoughts are that these disabilities are only 'invisible' because we keep them hidden. When I go to DD2's school with DD1, I have two choices. People there will not know that DD1 is disabled unless I tell them. Yes, she looks 'young' for her age. If she's not in her Mac Major, her posture, gait and stance is all a bit 'odd'. People would certainly notice that her speech is immature, if she spoke. But, largely, she is the girl with a big grin.
My choice is whether I let people see her behaviour, and say nothing, in which case they are likely to assume she is 'throwing a wobbler' or 'having a tantrum', or to simply say 'she's got a disability...' or 'she has SN'.
We as parents have every right to withhold that information from strangers. Of course we do. But with every choice comes a consequence. The consequence for many of our children, is that they will be judged 'naughty'.
We can complain that people are ignorant, but if we do nothing to change that, then ASD, 'squiffy brain' (in my DD1's case...no specific dx but MRI abnormalities), SWAN (Syndromes Without a Name), whateer, will remain 'invisible'.
But in my eyes, 'invisible' just means 'not categorised'. People, being people, live their lives by categorisation. We do it all the time. Short, tall. Fat, thin. Nice, horrible. If people don't have a category to slot our children's behaviour in, the category by default that is left is 'naughty'.
We want the world to accept our children as they are, disability and all. But, we don't want to tell the world that there is a disability to be accepted. How will that ever work??