please answer it by english

please answer it by english
Why do you think GAAP is needed when the practice of accounting for different industries is accordingly various by nature?

GAAP - Generally Accepted Accounting Rules
The Generally Accepted Accounting Principles, or GAAP for short, are a set of accounting rules used to standardize the reporting of financial statements in the United States. Understanding GAAP can help you make better investing decisions.
The common set of accounting principles, standards and procedures that companies use to compile their financial statements. GAAP are a combination of authoritative standards (set by policy boards) and simply the commonly accepted ways of recording and reporting accounting information.

Investopedia Says... GAAP are imposed on companies so that investors have a minimum level of consistency in the financial statements they use when analyzing companies for investment purposes. GAAP cover such things as revenue recognition, balance sheet item classification and outstanding share measurements. Companies are expected to follow GAAP rules when reporting their financial data via financial statements. If a financial statement is not prepared using GAAP principles, be very wary!
That said, keep in mind that GAAP is only a set of standards. There is plenty of room within GAAP for unscrupulous accountants to distort figures. So, even when a company uses GAAP, you still need to scrutinize its financial statements.