Why no warnings?

So wild to me that with all the medical info out there you almost hear nothing about autism until you actually find out your child has it. I was so worried about these super rare diseases when we were getting pregnant but autism was not even on my radar. I had even done a self assessment test when younger and tested high for Asperger’s but didn’t cross my mind that I could pass this on. How is something that is now almost 1/30 not mentioned by every medical practitioner / baby blogger / parenting guide out there? Has the be the most likely medical issue a potential parent might face at this point.