As for the second, the credibility of the whole social is not good enough. Outstanding payment is common among the chinese enterprises and government. Turnover rate of fund is comparely slow.

The bank caclulates loan interest as "simple" interest -- for every payment period, multiply the current outstanding principal by the current interest rate to determine the interest payment.

By contrast, rules are only executed when the conditions for that rule are exactly matched as a result of other system processing (for example, applying payment against an outstanding balance).