Why dont all companies use the same MANAGERIAL accounting systems?

The systems must provide different sets of financial statements; some companies dont provide outsiders with both an income statement and a balance sheet.

The systems must serve the competitive needs of companies working to uniquely serve specific customers in specific markets.

The systems are required to provide government data once per year, and the operating cycles of companies are often based on different seasons.

The systems are based on publicly available data which are posted in different databases for companies in different industries.