From the picture it looks like the rear bar on that cage is about 3cm (if not less) from your head, directly behind the seat head rest.
Your right the bar isn't far from the back of the seats but as I said the seats were just laid back in only for the purpose of the photos. Where they were you'd have to be 10ft tall to drive it haha but when they are bolted in the correct place they won't be that close.