Seatbelt tackles should never be any more than a yellow.
What about handoffs? Quite often they hit the shoulder/head area, but as they are usually done by the player attacking they seem to go unpunished, unless of course if it is a Wasps player doing it on a French player in which case it goes to the French courts and damages awarded against. the English Player (That's a reference to Phil Greening's hand off against Rougerie back in 2002 when Rougerie took out a civil action following throat injury and ended up with Greening being ordered to pay about £30k compensation)