Different hiring practices are needed for different businesses and different employee roles.
For example, defense contractors need to hire people who can obtain security clearances. That means that the civilian employers need to be quite diligent about checking for potential red flags such as excessive alcohol or drug use, a criminal record, etc. Similarly, criminal background checks are mandated for all teachers (you don't want to hire pedophiles!).
The level of responsibility of the employee is also an issue. Doing massive background checks and looking at Facebook profiles and such for a part-time employee who will be stocking shelves for a few weeks during Christmas rush is not only intrusive but a waste of company time. On the other hand, you need to check more comprehensively on managers and executives because of the potential they have to do significant harm to a company if they are dishonest, engage in insider trading, sexual harassment or discriminatory practices, are insensitive to diverse cultures, etc. A CEO or manager who gets drunk and tell racist jokes when meeting with important clients can really harm a company's reputation.