B4: Why can rear seatrests be locked via ZV?

Moin, have a smart question again: Why is it possible for the B4 but model 2.3 E to close the back seat backrests? So that you can no longer fold them over? And what’s behind it, I just don’t understand the meaning. Nobody breaks open a car to fold the seats or? If someone could explain it to me with more insight…. interests me just times^^ Greeting