OSHA collusion

I don't know if OSHA is just completely incompetent or colluding with Amazon. At our FC, there have been repeated complaints of unsafe conditions, but OSHA continues to look the other way. 

They sometimes let Amazon investigate and rectify on their own (which only happens superficially) and close the case. Other times, they've said they were going to investigate, but they seem to delay for months. After they eventually come in, they have a quick meeting with our FC leadership and then close the case as having been handled internally.  When asked for evidence, they accept clearly fraudulent evidence showing the issues have been resolved. They don't seem interested in challenging Amazon's dangerous work environment at all, despite the long history of injured workers.

Most importantly, OSHA has specific whistleblower protections, but they always seem to enable Amazon to find out who complained to OSHA and then they're quickly (but quietly) shown the door. 

Is this happening at all Amazon's FC's nationwide or just here?