Because neither you or greatwhiteshark are being honest in your assessments. A good practice when something "just doesn't make sense to you" is to assume it is your reading of the situation rather than the situation itselfI just don't know how we reached a point where a player can show poor technique in tackling, give someone a smack on the chops, and not give away a free kick merely because the bloke who has won the footy was trying to avoid the tackler.
The high tackle (as well as the push in the back in tackling situations) is very hard to adjudicate in the professional era. Players taking possession and whose first instinct is to try to draw high contact is neither good for the game play or player safety. Likewise players entering contest head first (which, mind you are generally rewarded with high contact.