Scanning BP upon boarding
 

I saw this for the first time in summer 2019 and thought nothing of it at the time but does anyone know when and why KE those BP scanners ?

I'm talking about the yellow and black ones used when you board.

They want to make sure you're on the right flight (some news stories about people on other Korean airlines getting on the wrong flight and wrong airline all together, like they swapped boarding passes two people). Also they want to guarantee that you show up - they have a new no show policy and penalty because of Kpop fans getting on flights and de-boarding after taking pics (costly to fix that mistake) or just getting a ticket to follow the stars around the airport and not take a flight.