You may not, but the super rich could definitely spend big $ offshore to save money, and might be able to leverage or further profit from this.
Sure, they definitely would. Especially using money they also earned offshore, so it would be very hard to track. Maybe we should also have some sort of required reporting of income earned offshore, and of bank accounts, etc. I'm not sure taxing your vacation in Niagara is the best way of getting at that.
By which I mean, you can't avoid complexity.