In Rain Man, a large majority of the film is premised off Charlie wanting to get the $3 million estate inheritance from Raymond, issued by their father after his death.
Well, IIRC, Raymond was sent to a mental institution at a fairly young age, and has been there ever since. Now, I can understand the argument of: well, since Raymond was placed in an institution for most of his life, his father giving him the $3 million estate is his way of making up for neglecting Raymond all these years..
However, if they know that Raymond's mentally retarded, then, why give him the responsibility of such a large estate? Or, even if it was cold hard cash, what could Raymond ever do with it if he's stuck in the mental institution, and with a limited mental capacity?
So, ultimately, was their father's issuance of the estate to Raymond instead of Charlie a gesture of apology to Raymond, or, more of an intentional insult to Charlie?
It could be argued that, if his father really was sorry for placing Raymond in the mental institution all these years, then, he could have issued the inheritance to Charlie instead, but with the stipulation that some of that estate/money be applied to taking care of Raymond (i.e., getting a small apartment for him and hiring an at-home nurse/caretaker).
With this approach, Raymond and Charlie would still have the chance get to know each other, etc., and not too much of the story would change, and both brothers would perhaps [loosely speaking] equally benefit..