Some things to ponder:
How is it vintage races manage to have far fewer incidents?
[Before anyone chimes in about high speed parading I would suggest you've never vintage raced. Egos & the desire to win abound there as well. Pretty sure Tim isn't building a Mustang to parade around].
Years a go a dear friend asked me how come men act like pigs, to which I answered "because you let them".
Every time a group gets out of hand it's because we let them.
Think I'm exaggerating? Sports Renault (now Spec Racer Ford) was known as Sports Rambo & we all know about Spec Pinata (Note SM was very well behaved at the RunOffs this year).
This is and has been an on and off problem for the SCCA for some time; years ago I was at a regional where Marge Binks was the Chief Steward. The Spec RX7 group were driving like buffoons, she put them on notice. Lo and behold their standards immediately improved.
Randy Pobst (among others) worked hard to establish passing standards but at the end of the day they need to be enforced.
Rubbing is not racing at the amateur level; that is total BS. For a case in point see the 2021 F500 RunOffs race; two drivers going at it hammer and tongs while showing each other great respect.
How to fix it:
1. You need to be clear about the expectations and that over aggressive driving will not be tolerated (even at the RunOffs).
2. Take this out of the drivers hands; there is a culture of not wanting to protest, if there is contact (incidental or otherwise) both parties should be summoned to the stewards. (this is what happens at vintage).
3. Weed out the bad apples. Now that on board cameras are required it's much easier to sort how who did what. Those who repeatedly send it & cause crashes are not only damaging peoples cars, they're damaging your participation numbers.
Finally:
Yes, some drivers will claim you've wussified the racing and threaten to leave but most of us would welcome the discipline.
This is what I once told a very talented driver who had a habit of bouncing off people "you are pretty much inch perfect everywhere, well how come you can't be inch perfect when you're next to other cars?"