Only 10% of bills become laws because the legislative process is rigorous. By rigorous, I mean that the bill must be examined by legislative committees and subcommittees with various experts testifying for and against various aspects of the bill. There are usually amendments and compromises along the way to becoming a law. If the process were not rigorous, then we would have many bills passed that were not examined thoroughly and there would be many unintended consequences. After all we want good laws that improve our lives not laws that make things worse.