Seats in the upright position
There is one seat type not required to be returned to the upright position, and that is the Business class seats on Air New Zealand and Virgin Atlantic. They are arranged in a herringbone layout and the (fat) seat belt contains an airbag. My memory is that you can't be in the lie-flat position, (which is on the back of the flip-over seat (really!)) but I'm not a frequent flier at the front of the plane, more's the pity :-(.
I suspect the airbag is key here.