I believe that most compliance issues are unintentional. While there may be some employers how knowingly risk noncompliance as a business decision, I think that in most instances—particularly those that you hear about—result from misunderstandings of what the law requires or failures by managers and H.R. personnel to enforce and follow through with established policies and guidelines.
It is easy for H.R. directors, corporate counsel, and even outside counsel (such as myself) to promulgate and issue policy after policy from the comfort of our offices, wholly detached from the places where the policies must actually be performed. Compliance, for the most part, comes down to finding and establishing a first-line management team that understands the policies, the purpose behind the policies, and the importance of implementing and enforcing the policies. Upper management, on the other hand, needs to recognize that certain benchmarks and productivity goals may suffer as a result of hard and fast compliance enforcement. It is the first-line manager that attempts to inflate numbers and productivity to the detriment of H.R. compliance (in order to impress his or her managers) and the upper level management that turns a blind eye to noncompliance (often for the same reasons as the first-line manager: approval from superiors, the bottom line, pressures within the organization, etc.) that creates the environment for numerous compliance related issues. Add in a few highly technical and difficult to understand (and more difficult to apply) federal and state laws and the cost of compliance can quickly escalate.
Ultimately, I believe the answer to your question is that the cost and the amount of time it takes to “fully comply” with existing laws and regulations are the cause of of inaction by owners and managers. Such noncompliance is not intentional. It simply costs to much and takes too much time to fully understand, implement, and enforce all the requirements imposed on employers. This is not meant to excuse employers; it is merely an attempt to explain how and why companies like Wal-Mart, UPS, Target, and FedEx can have so many compliance issues. For better or for worse, compliance detracts from productivity and many owners and managers will lean in favor of productivity over compliance.
All that said, issues related to the FLSA and its state law iterations are the most problematic. Whether it is wage and hour, fraternization, meal and rest breaks, overtime, or worker classification, it is the FLSA that creates the most compliance issues. It is somewhat ironic that the objective criteria of the FLSA is often more difficult to follow than the more subjective requirements of Title VII, the FMLA, and the ADA.