The trouble with this is that, no one even knows the actual cause.
I don't mean, they haven't found it.
I mean, they haven't even considered it a possibility yet.

That said, the connection between vaccines and autism cannot be proved.
It is statistics.

Not every child who develops autism was vaccinated.
Not ever child who was vaccinated develops autism.

However, you find a great deal of circumstantial evidence.
Now that more people are aware of the side effects of vaccines, the correlation between when the child got vaccinated and when the symptoms started are much more noted and documented.

Further, there is an evil organization that is out to poison us and keep us dumb. This same group has lead the way in programming people to believe that vaccines are safe, trustworthy, scientific and immunize people. So, you have a group that is dedicated to their task of maintaining that false front with all the money in the world. And you have an army of people programmed to parrot the propaganda.