Originally Posted by
televisor
Or there could be an emergency going on, with passengers unaware, and the pilots too busy focusing on preparing for landing ASAP and too little time to notify the crew, never mind time for the crew to check that seats are back up. Or even worse you're already on your way down to an off-runway landing for whatever reason.
By the time you're at 10k there's a lot more time (height) before you can realistically reach the ground, at which point it's actually ok to recline.
Pretty easy to tell if the aircraft is gaining height or not on the takeoff and even easier to tell you’re coming back around to land. I wouldn’t be overly worried about it. In smooth flight on most foreign airlines the seatbelt sign is even off long before 10k.