Are you sure? A lot of "credit cards" in China are actually debit cards, where you must deposit money in your account up-front before you can spend. I don't see any reason why banks would make it hard for people to get these, since there's virtually no risk of bad debt.
However, there are also potentially strong reasons to avoid it.
1. China dissuades capital exodus. (They actually have a whole government bureau for this, the Foreign Exchange Management Bureau or 'waihuiguanliju')
2. My recent travels about Southeast Asia suggest that the government-run centralized interbank settlement network 'China Union Pay', is being supported by the government as a regional alternative to the de-facto global defaults Cirrus/Maestro (Mastercard) and Visa (Bank of America).
Anyway, the why doesn't matter. It's really the situation.
That assumes that transactions are always processed immediately. This is not the case. Some gas stations, and convenience stores, for example, will wait up to a week before actually charging your card (they frequently just check to see if you have funds available at swipe time). This saves them money on batching charges. As a result it is possible, with a debit card, to run up charges that exceed the available balance. That's why a credit check is required to give out a debit card with a visa / mc symbol on it.
So, even in the US, if you have bad enough credit, you may not be able to get a debit card even though in theory you shouldn't be able to charge more than you have.
Are you sure? A lot of "credit cards" in China are actually debit cards, where you must deposit money in your account up-front before you can spend. I don't see any reason why banks would make it hard for people to get these, since there's virtually no risk of bad debt.