The most significant cultural nuance of 来 (lái) lies in its strict speaker-centric perspective. In English, you might call a friend who is at home and say, “I'm coming over,” even though you are moving *away* from your current location. This is impossible in Chinese.
The use of 来 (lái) vs. its opposite 去 (qù) is determined by the direction of movement relative to the speaker (or the speaker's conceptual “base,” like their home or office). If the movement is toward the speaker, you must use 来. If it's away, you must use 去.
This reflects a less flexible but more precise way of describing movement that is rooted in one's own position. This principle extends to other directional complements like 上来 (shànglái) (to come up) and 上去 (shàngqù) (to go up). Understanding this perspective is crucial for avoiding common beginner mistakes and truly thinking in Chinese.
Additionally, the common phrase “我来” (Wǒ lái), meaning “Let me do it,” subtly reflects a proactive and helpful attitude, often used among friends, family, or colleagues to offer assistance, such as paying a bill or carrying a bag.