Lowering the tackle height saw no less head injuries in this trial
https://www.bbc.co.uk/sport/rugby-union/47000468
“RFU tackle height trial ended after concussions rise in Championship Cup”
I’d suggest, forcing tacklers to go low is dangerous, especially where a player goes for a gap only to be double tackled. The head clashing between tacklers will sky rocket. Not only that but knees to the head of the tackler.
WR have really ballsed this one up. The tackles they deem to be cards all happen very frequently in a match, are fairly difficult to avoid and will continue to happen. The ref or TMO if looking, I'm sure could find half a dozen such collisions in a match.