Power
This. This is why you do what you do. Yeah, no, sure—public safety and all that. Of course. But the power is really nice. And that's okay, because someone has to do it. Not everyone has the chutzpah necessary to carry the clipboard and check off the boxes.
When you walk in to whatever workplace you're walking into, the first thing you'll notice is everyone seems to be in a heightened state of alert. This is because your mere presence affects how each employee does their job, both today and in the future. If the first person to greet you isn't the manager or supervisor, someone will run (sometimes literally) to the head office and gently scream of your arrival, usually wide-eyed and sweating from panic.
Everything and anything you ask to see must be shown to you, from employment records to equipment to storage to where the employees change or shower. You'll wander the premises, your every "hmm," sigh, and side-eye giving the supervisors mild heart attacks.
This level of power is the same whether you work for a company, an insurance agency, or the government. However, there's one very important difference between them: local, state, and federal authorities have the extra power to fine businesses for their lack of compliance to health and safety regulations (source). When you start going after an owner's pocketbook, they tend to start listening to what you have to say.
If the issues are serious enough, you might even close the business down for a while, or for good. That's a lot of power from just a couple strokes of the pen.