The SEC requires certain disclosures with regard to "insider selling". Those required disclosures do not mean every insider on the planet complies. They just mean if they dont, theyre in violation.
Do a quick search and see the long list of insiders brought up on charges for NOT disclosing... and they are the only ones that were caught. Another component of not reporting are the consequences. In many, many cases the punishment is a pittance compared to the proceeds of sale received
Remember, this isnt college where we manage an imaginary widget company. This is the real world. even worse, this is the world of penny stocks!!