An OSHA violation is a serious matter. Many of them can result in injury or death. Some violations are obvious and easy to spot while others require training and a comprehensive understanding of the requirements in order to detect them.
For example, improper Lockout/Tagout of energized equipment or machine guarding, although not simple, might be easier to notice and correct than electrical code violations that require a detailed understanding of the written rules and are likely to be unnoticed by many at the site.