Who can do entries on Carfax for vehicles?

Is it just insurance companies and police that can add to a particular vehicle's history on Carfax or can an individual who has verified info and due diligence on Carfax's side add to vehicle history?

Repair shops can do it too, but it is useless from my understanding as the shop has to pay for it.

I know the DMV can do it, and so can your average fat fingered luber-goober at the iffy lube.