“Well, it the case of my SiL’s grandparents, they had a car dealership and they never got it back.”
Your SIL’s grandparents were given a bit of time to liquidate those assets. It goes without saying that they were at such a disadvantage that they were unable to arrange fair prices for anything. One must assume that they took a huge loss, including the rights to the dealership itself.
That was extremely unfortunate. However, the circumstances of the war demanded it, just as they demanded that some men be forced to enter the armed forces and give up their very lives.
That said, I do think we should have done a better job of making the internees whole when the war was over. However, not proceeding with the internment would have been unconscionable.
“Your SIL’s grandparents were given a bit of time to liquidate those assets.”
That is simply a statement that is untrue. And any way just how would you know in this particular instance that what you said was true?