And the reason behind that? Copy from other comments, "So China can't spy on Americans and astroturf propaganda", swap China/America
The Chinese versions of these services are walled off from the rest of the world (otherwise the ICP license probably ends up applying to the worldwide service), so this is not even a plausible explanation.
Further, asserting that the requirements imposed by the ICP recordal as being equivalent to following laws in other democracies is laughable; since most democracies make considerations towards good faith motives towards following a law even though there might be misses otherwise, not to mention the kind of content being censored.
https://en.m.wikipedia.org/wiki/Dragonfly_(search_engine)
Microsoft Bing has been merrily operating in China for a very long time: https://www.bloomberg.com/news/features/2024-03-07/microsoft...
The issue here is probably caused by the requirement for an ICP recordal which requires removal of violating user-generated content within 15 minutes, which is probably a very tight deadline, probably coupled with a strong false positive rate which is why said companies are also hesitant to introduce automation.
It could also be argued that Tiktok is not completely value-aligned with US interests, although this has not been provably shown and whatever we have thus far is speculative.