They don't need to. These companies have self-sufficient intelligence operations, and they employ seasoned experts. At an outfit like Google, and that may involve too many people overriding checks to be worth the risk of a leak. It's hard to say, I've never worked for Google.

The Pinkertons are still active in union-busting, and they are retained by shiny "Great Place To Work"-type businesses. They're just covert now. When somebody is giving off too many pre-crime vibes at that kind of business, HR can easily get rid of them for unrelated reasons, and gaslight them into thinking it was their fault all along.

Never talk to HR. They are the secret police.