This happens to ALL colors of paint and not just white. Just more noticeable on white. My greystone jeep has plenty of it. I don't worry about it on the jeep though. I haven't heard of that IronX before, looks cool. Might have to give it a try. I have always felt the claybar did a fine job of removing the contaminates and then a good wax keeps it safe for a while. I am notoriously bad at exterior maintenance, so I am typically a clean and wax in the fall and a clean and wax in the spring guy.
I have thought about trying one of those spray on nano coatings just to see if it keeps things looking better a little longer.
My wife does have the pass to the car wash and hits the car wash fairly frequently but that just doesn't do the same as a good hand wash. I made the mistake of buying another black suv, didn't learn my lesson the first time I guess. White is by far my favorite vehicle color.