The hospital I visited for my first plastic surgery consultation asked for my ID, so I gave it to them thinking it was all like that.
 
After going to three more places and having surgery at other hospitals, I realized that none of the hospitals directly asked for my ID during consultation.
 
I had thought that a resident registration number would be needed because it had to be linked to the national health insurance system, but I found it questionable that the ID card itself was requested. Is this the case in other hospitals too??