they do have railing lol. you can see it on the side story where taeju got embarrassed
He's "broke" + selling their house would pay for another one with no stairs (which I'm presuming is what he meant). What makes him actually fkn loaded is being able to pay for daycare/preschool and the birth of a child whilst slacking his butt off at home
Children are NOT cheap but a new house in comparison is
So, I went back to the chapter cause I thought I missed something and you are half correct. From what I saw they have two different sets of stairs in the house. The main one I was talking about and the one they keep tripping on is the one without the railing. Apparently it has some like fancy thin metal columns that you could kinda use as a railing but is pretty inconvenient.
I could never be that rich. To have the option to move into a new home because of the stairs is crazy. Just add some type of railing.