Do ALL government employees take bribes?

Bribing police is quite common to make them work efficiently and fast but do ALL government employees receive bribes? If yes, why and how? Suppose a person is working in home ministry, railway ministry, airport authority of India etc then why do they get bribed and by whom they get bribed?

People bribe police so that they don't have to pay fine or get their work done early but why and how do normal government employees receive bribes?