Bureaucracies enable the operation of government by creating a system for transmitting the orders of the upper levels of government down to the lowest levels at which they are actually applied to people.
For a government as large as that of the United States, it would be impossible to function well and equitably if there were no bureaucracy. Each local office in such a system would be relatively autonomous and different offices would have different policies. This would not be fair or effective. Instead, there is a bureaucracy. Each level of the system is supervised by the level above it. The laws that are passed by Congress and the rules that are written at the top of the bureaucracy are transmitted down from level to level. In this way, it is possible for government to operate in a way that is fair and relatively efficient.