Are you sure immigrants can all vote in their home countries if they don't live there?
I am American, and can vote in local elections in Norway because I've lived here, legally, at least 3 years. This isn't uncommon, and I find it fair since these are the things that impact me the most. I cannot vote in national elections. Also fair. On the other hand, the American voting forms for me make sure to ask if I ever intend on living there again. I have limited voting in the US, and I sure as heck don't expect any politician to do anything for me unless it'd look good for propaganda.
This is all besides the point: the original post was talking about folks that cannot participate in the democracy they live in.
I'm not even sure what you were trying to say with the last comment. Could you please explain it?