Both Google and Facebook once operated in China, but after the multiple terrorist attacks, they were unwilling (or unable) to comply with Chinese laws.
That’s why Skype and iMessage are available in China, they comply with Chinese laws.
Let’s be real, the Chinese government only wants to allow internet companies that will allow them to monitor all communication and traffic between Chinese citizens so that they can stamp out any dissent. But dissent and disagreement is not terrorism. It’s both creepy and Orwellian.
'Terrorist attacks' from who exactly? When French or Polish resistance members assassinated Germans, I bet the Nazis thought that was 'terrorism.' The Chinese government likes to cry and moans about 'terrorism' from Tibetans and Uyghurs, but the CCP are the real terrorists in these situations. Any American company that cooperates with them are abetting genocide.
The main difference is that the Chinese only have one party -- which means they don't have to pretend their votes matter which might even be seen as an improvement (at least honesty wise).