We live in an age when legislatures create laws from scratch. Laws were not always created de novo. Earlier, laws were discovered rather than created. A conflict between two parties was seen as a problem to be solved. A solution was discovered by wise people working on the problem, just as are solutions to most other problems. Once a good solution was discovered, it would be applied to all further instances of that problem. Thus was the law born.
Legislatures, on the other hand, make up laws even when no problem is to be seen. This has a well-known corrupting influence on legislatures, what with people convincing a legislature that a personal or corporate problem is actually a public problem. Beyond that, though, a legislature, in my experience, will create more laws than it is willing to pay to enforce.
By corrupt, I mean that they take money for a service with no intention of supplying that service.
Having a surfit of laws and a deficit of funding puts the executive body into a quandry. Since it cannot enforce all the laws, it must pick and choose. Once it has this discretion, it has the ability to grant favors. With freedom comes responsibility, or irresponsibility in this case.
Now, I don't want anybody to take this as a blanket condemnation of all executive bodies. I'm merely pointing out the economics of the situation. The legislature (itself an easily corrupted organization) has created an incentive for the executive body to be corrupted as well.