Romney really is incapable of straying off-script.
Either that or he's succumbed to an outdated belief that every audience he speaks to is hearing his routine for the first time -- as if every form of media hasn't been broadcasting every word that comes out of his mouth to the masses 24/7.
Or maybe he just thinks he's like a comedian or musician and figures that each new audience is expecting to see him perform his greatest hits and will leave disappointed if he doesn't.
Oh yeah, and his wife drives a couple of Cadillacs. He's just your average guy.