Or that you recognize that they have retirement savings products that are essentially not biased in favour of the highly compensated. The qualified plan rules serve much the same purposes the registered plan rules do here.
If somebody moves across the border, they can't currently transfer their retirement savings. If you get married and move to Arizona, you're going to run into a whole bunch of tax complications because you want to cross the border. I can say from personal experience, you face a lifetime of dual tax returns.