South Korean companies undoubtedly have greater legal recourse to challenge the government, but I am unpersuaded that the chaebol exercise that right particularly often. The impeachment of president Park does indicate an appetite for change, but South Korea has a long history of corruption, cronyism and state-sanctioned monopoly abuse.
Er... just to clarify: Samsung was deeply inter-wined with the government before(from the 80s to ~'17), I’m not sure if NIS has actually requested Samsung’s data but I suspect Samsung could give out such data.
However most companies don’t; for example, the biggest chatting app Kakao (think as WhatsApp in the US or WeChat in China) refused to provide information; opened the fact that NIS requested info to the public; and revised the chatting system to only save the message for 3 days in the server and added a end-to-end encryption mode.
Just wanted to point out that South Korea’s situation is less like China but more like the US.