The New Zealand players who were bitching about cards for Direct head contact during the recent three test series need to read these articles. World Rugby has done so much better than American Football and cycling about dealing with these issues. The current crop of players probably won't have these issues because world rugby is cracking down on tackling. If you:
1. Go in upright
2. Make head contact
3. Demonstrate a degree of recklessness
4. Initiate a high degree of danger
RED CARD plus multi-game suspension.
You can't lead with the head, you can't drop a player on his head, and starting next season the highest point of tackling permitted will be midway from waist to shoulder, to eliminate tackles that ride up to the head.
In addition, players and coaches no longer have discretion over head injury assessments; if the ref says you need your head looked at, you need your head looked at.
The other great thing about Rugby is that the rules are made by referees. Thus, no big financial interest is getting in the way of rule changes.