What's important to also realize is that the solution isn't to make the system harder to use, because a side effect of that will be that people who NEED said system will find it inaccessible.
e.g. disability insurance is rife with fraud. Insurers combat this by auditing nearly all applications for fraud, and this has the effect of denying recompense for those who are truly disabled, for they do not, will not, or cannot jump through all the arbitrary hoops introduced by the insurer to combat fraud.
I don't have a solution for fraud and abuse of systems, however.