They are blocked because they don’t censor content. If they did agree to, they would be allowed - just like Microsoft, Bing, Apple, and a handful of other digital products are not blocked in China.
Edit: for those downvoting me, Google literally shut down their China operations because they were unwilling to comply with censorship requirements. Conversely, Google and other US companies seem completely willing to comply with national security letters that compel them to spy on non-US persons, which should make other countries where US companies operate equally uneasy.
Edit: for those downvoting me, Google literally shut down their China operations because they were unwilling to comply with censorship requirements. Conversely, Google and other US companies seem completely willing to comply with national security letters that compel them to spy on non-US persons, which should make other countries where US companies operate equally uneasy.