I, too, wonder what's the difference between a sale to a "relative" and any other sale? It would also seem that right now, given the housing market "crisis," the sales price would be at a comparatively low amount, so that the "pop-up" value on any residence would, if anything, be artificially low.
So why not also exempt from the tax "pop-up" all sales by the elderly, the disabled, the unemployed--or why not exempt everyone?