As a foreigner there are certain places in China they won't let you travel through and even certain cities you cannot stay in overnight. This often coincides with where mining and industrial production are.
China has an impressive ability to cover up the truth.
I'm sure there's a lot of land in US, you'd get promptly kicked out of by various security forces of corporations doing nasty stuff there.
Last I went to China (mid-late 2010s), you could visit the less well off areas and off beaten paths in much of China as a tourist without too much hassle.
The issue is most people don't. China is hard enough without Mandarin fluency, but going to urban villages where migrant workers live or Tier 3/4 cities where the majority of manufacting happens is an added level of difficult for "soft" people.
Most tourists perfer to stay in their tourist bubbles, which tend to be a monoculture globally.