Not just China, no country on earth should be naive enough to let the US surveillance corporations operate within their borders. Here's a good video on why the PRC keeps them out.

But all these experiences tell me Chinese society is not accepting of even apparent criticism, which does not look like a free society to me.

The PRC doesn't just allow criticism and freedom of speech, it acts on it, unlike western countries where everyone (arguably) has the freedom to shout into the void and change nothing. The CPC is the world's biggest pollster, which constantly gets feedback from its citizens, and acts on them.