I'd be interested in knowing whether those stars are paid as much to do cartoon voices as they are paid to do regular movies. I'd bet they're paid a lot less because it's less work, right? No messing with costumes or makeup, or reshooting scenes because they don't look right. A flubbed line can be fixed in editing. They don't need to memorize their lines because they can read them. They don't even need to be in the same room with their co-actors.
Acting is just as unfair as music. Some get rich while others have a hard time making a living.
It's hard to believe the rich ones really deserve it.