This is so that other businesses that may be able to come up to them and change or take them down stay low so that they can't. This would range from destroying the businesses products or equipment to assassinations of certain people. The government then pay money to the mafia or assassin, and a cut of whatever money the mafia made in that process. Government then give the mafia freedom to do their own things, their own set of rules in this case. Now the government stay nice and big, and nobody gets too powerful in the governments eyes.