Each country has the right to say if businesses or entities of a foreign country can operate in their borders. The US Govt is rarely directly involved with operationing a company or business, with the biggest exception being the US Postal Service. So while they might make rules and regulations for how companies can do business, these businesses are privately owned, what information they gather on clients or users is for commercial use, typically for advertising purposes.

With Chinese companies, this is not the case, even companies that are technically privately owned are heavily managed by the CCP if not directly operated or owned by an official member of the govt. So while in the US if a company like Instagram or Twitter was told by the US govt to hand over information about certain individuals, without a warrent clearly defining what data to hand over and the reason for it, those companies can and in the past repeatedly have used legal means to resist and deny those demands. This isn’t a thing n China, and there is a lot of rumors that all the data these Chinese originating platforms collect by default goes to the Chinese govt, who can use it for anything from espionage, using insider information gathered illegally to manipulate markets or officials, to even things like blackmail or planning military actions in extreme cases. The CCP and all their associated companies have repeatedly shown in the past they don’t care about the rights of citizens in other countries, copyright laws or intellectual rights, and would be more than happy to turn every teenagers smart phone into a listening device into peoples homes and tailor content shown to individuals they identified as someone they can manipulate to radicalize them in a manner that suits them without any regard to that persons wellbeing.

If you think the US Government is untrustworthy (which, yeah it’s not) then you should be absolutely horrified at the thought of ever allowing the Chinese Govt and the CCP having access to any of your personal life or allowed to put software on your device and partake in a social network they curate and moderate.