Well, it is not supposed to help the public. It is supposed to help the government. More specifically, it helps those employed by the government. These fines often get injected directly into the budgets of agencies and can be used for any number of "off budget" expenditures, including travel to conferences and overtime for staff.
Fines are thus often large enough to help a particular office doing the investigation, but not large enough to be putative to a corporation. Indeed the extent to which it punishes anyone, it is the shareholders and consumers.