Can Korean Air add up the weight of checked baggage?

pu1. I know that Korean Air doesn't do it

2018-07-25

OK

pu2. Korean Air, too. They don't do it these days

2018-07-25

OK

pu3. They don't want to add it up because it's hard to move it if it's over 30kg
It's better to share your luggage in advance

2018-07-25

OK

pu4. In the past, I used to do it to a certain extent, but now I'm not doing it

2018-07-25

OK